With regards to domains, the term 'brandable' is applied to non-words that are (nearly always) pronounceable, non-dictionary words, easy to type and usually have a slight 'quirky' edge to them.
The idea is you or whomever you sell the domain too is going to build a brand around this name.
'google' is an excellent example of what would have been classed as a brandable name 15 years ago. (It's not a dictionary word, you can pronounce it, it's easy to type and it's a little bit quirky- a variation of the humorous-sounding word word googol)
It may be hit-and-miss whether a brandable name will ever be worth anything, your best bet if you're looking to register some is to keep it short, in a CVVCV or CVCVV format or similar. (where c = constonant and v = vowel)