I have just researched the word Twitter and apparently it's not trademarked.
I'd be fascinated to know of what your "research" consisted.
First off, as will be printed on my tombstone one fine day, there is NO requirement in the US that a trademark be registered. Are you aware of anyone who is using "Twitter" as the distinctive brand for an online communication service, such that when relevant consumers see "Twitter" then it calls to mind a particular service which originates with a particular provider? If so, THEN THAT IS WHAT A TRADEMARK IS.
And, if you are not aware of a particular online communication service known specifically and distinctively as "Twitter", then please call 911 and see if they can pick up a pulse or any brainwave activity.
Secondly, despite the fact that trademarks do not have to be registered, in this instance there are quite a few:
Word Mark TWITTER
Goods and Services IC 038. US 100 101 104. G & S: Telecommunication services, namely, providing online and telecommunication facilities for real-time interaction between and among users of computers, mobile and handheld computers, and wired and wireless communication devices; enabling individuals to send and receive messages via email, instant messaging or a website on the internet in the field of general interest; providing on-line chat rooms and electronic bulletin boards for transmission of messages among users in the field of general interest; providing an online community forum for registered users to share information, photos, audio and video content [ abut ] * about * themselves, their likes and dislikes and daily activities, to get feedback from their peers, to form virtual communities, and to engage in social networking. FIRST USE: 20060831. FIRST USE IN COMMERCE: 20060831
IC 041. US 100 101 107. G & S: Providing on-line journals, namely, blogs featuring user-defined content in the field of social-networking. FIRST USE: 20060831. FIRST USE IN COMMERCE: 20060831
IC 045. US 100 101. G & S: Providing a website on the internet for the purpose of social networking. FIRST USE: 20060831. FIRST USE IN COMMERCE: 20060831
Registration Number 3619911
Registration Date May 12, 2009
Owner (REGISTRANT) Twitter, Inc. CORPORATION DELAWARE 1355 Market Street, Suite 900 San Francisco CALIFORNIA 94103
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Word Mark TWITTER
Goods and Services IC 006. US 002 012 013 014 023 025 050. G & S: PROMOTIONAL ITEMS, NAMELY, METAL LICENSE PLATES. FIRST USE: 20090410. FIRST USE IN COMMERCE: 20090410
IC 016. US 002 005 022 023 029 037 038 050. G & S: PROMOTIONAL ITEMS, NAMELY, PENS, PENCILS, BUMPER STICKERS, STATIONERY AND GREETING CARDS. FIRST USE: 20090410. FIRST USE IN COMMERCE: 20090410
IC 021. US 002 013 023 029 030 033 040 050. G & S: PROMOTIONAL ITEMS, NAMELY, DISHES, IN PARTICULAR MUGS AND GLASSES. FIRST USE: 20090410. FIRST USE IN COMMERCE: 20090410
IC 022. US 001 002 007 019 022 042 050. G & S: PROMOTIONAL ITEMS, NAMELY, LANYARDS FOR HOLDING EYEGLASSES AND KEYS. FIRST USE: 20090410. FIRST USE IN COMMERCE: 20090410
IC 025. US 022 039. G & S: CLOTHING, NAMELY, T-SHIRTS, SWEATSHIRTS, SHORTS, PANTIES, HATS, VISORS, SOCKS, TANK TOPS, JACKETS AND POLO SHIRTS. FIRST USE: 20081112. FIRST USE IN COMMERCE: 20081112
Registration Number 4362656
Registration Date July 9, 2013
Owner TWITTER, INC. CORPORATION DELAWARE 1355 MARKET STREET, SUITE 900 SAN FRANCISCO CALIFORNIA 94103
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Word Mark TWITTER
Goods and Services IC 038. US 100 101 104. G & S: Telecommunications services, namely, providing online and telecommunication facilities for real-time interaction between and among users of computers, mobile and handheld computers, and wired and wireless communication devices; enabling individuals to send and receive messages via email, instant messaging or a website on the internet in the field of general interest; providing on-line chat rooms and electronic bulletin boards for transmission of messages among users in the field of general interest; providing an online community forum for users to share information, photos, audio and video content about themselves, their likes and dislikes and daily activities, to get feedback from their peers, to form virtual communities, and to engage in social networking. FIRST USE: 20061201. FIRST USE IN COMMERCE: 20061201
IC 041. US 100 101 107. G & S: Providing on-line journals, namely, blogs featuring user-defined content. FIRST USE: 20061201. FIRST USE IN COMMERCE: 20061201
IC 045. US 100 101. G & S: Online social networking services; providing a website on the internet for the purpose of social networking; providing on-line computer databases and on-line searchable databases in the field of social networking. FIRST USE: 20061201. FIRST USE IN COMMERCE: 20061201
Mark Drawing Code (5) WORDS, LETTERS, AND/OR NUMBERS IN STYLIZED FORM
Registration Number 4179739
Registration Date July 24, 2012
Owner (REGISTRANT) Twitter, Inc. CORPORATION DELAWARE 1355 Market Street, Suite 900 San Francisco CALIFORNIA 94103
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Word Mark TWITTER
Goods and Services IC 009. US 021 023 026 036 038. G & S: Software and software applications to enable transmission, access, organization, and management of text messaging, instant messaging, online blog journals, text, weblinks, and images via the internet and other communications networks; computer software used to enhance the capabilities and features of other software and non downloadable online software; software for accessing information on a global computer network; downloadable software via the internet and wireless devices for accessing, sending, and receiving information on a global computer network; downloadable software for computers, portable handheld digital electronic communication devices, mobile devices, and wired and wireless communication devices for facilitation of communication and data transmission in the field of social networking; downloadable software in the nature of a mobile application for use with computers, portable handheld digital electronic communication devices, mobile devices, and wired and wireless communication devices for facilitation of communication; downloadable software in the nature of a mobile application for social networking; downloadable software in the nature of a mobile application for real-time delivery of data, messages, location, photographs, links, text and other data related thereto; downloadable software to facilitate online advertising, business promotion, connecting social network users with businesses and for providing strategy, insight, marketing, and predicting consumer behavior. FIRST USE: 20061000. FIRST USE IN COMMERCE: 20061000
IC 035. US 100 101 102. G & S: advertising and marketing; advertising services; online advertising and marketing services; business data analysis; promotional services; business networking; online service for connecting social network users with businesses; business monitoring and consulting services, namely, providing strategy, insight, marketing guidance, and for analyzing, understanding and predicting consumer behavior and motivations, and market trends. FIRST USE: 20100400. FIRST USE IN COMMERCE: 20100400
Registration Number 4422235
Registration Date October 22, 2013
Owner (REGISTRANT) Twitter, Inc. CORPORATION DELAWARE 1355 Market Street, Suite 900 San Francisco CALIFORNIA 94103
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.....and a couple of others.
So, somehow, your research managed to miss all of several US trademark registrations and a multitude of foreign and international registrations.
Maybe Twitter on its own is a trademark, but using the word in a different context for example cbdtwitter may be ok. For example, "those birds Twitter all day long" cannot be a TM infringement surely
Let's start with the second part of that first. What, in this universe or the one you occupy, does "CBD Twitter" have to do with birds tweeting?
In other words, what is the conceivable context of use for "cbdtwitter.com" that has anything to do with the dictionary definition of the word "twitter"? And, by dictionary definition, mind you, we are NOT talking about any sort of online communication service, social network, text messaging, or any of the other types of things for which "TWITTER" most certainly IS a well-known trademark. In other words, just what is this "different context" in which you believe the domain name (a) has any sort of independent commercial value, and (b) has nothing to do with the services for which TWITTER is a trademark?