Again, look at my links. In plural it clearly does exist. I am fluent in Spanish. So you can't use that reasoning on me.
So far you are speaking from your own understanding. Post some authoritative links that support your view.
A grammatical characteristic of nouns, articles, adjectives, participles and pronouns that classifies them in two groups is called gender: masculine and feminine. Adverbs and verbs (except participles) lack gender and a certain number of particles have a neutral gender.
The genre of the words of things is what the use has assigned them (often inherited from Latin).
The gender of the words of people is often, although not always, the one that corresponds to their sex, especially when referring to the origin (German, German) or occupation (fruit, fruit).
The genre of animal words is often independent of sex and is the one assigned to them by the use.
The common word denomination (in terms of gender) applies to those that allude to people and that have a unique form for both genders (the athlete, the athlete), while the ambiguous word (in terms of gender) refers to those of things and concepts that can be used in both genres (the sea, the sea). Strictly speaking it is not about two other genres, but allude to the property that certain words have to be able to be used both as masculine and feminine, for which today the denominations, habitual yesteryear, of common gender and ambiguous gender are hardly used anymore.
Formerly included one more genre, the epiceno, but nowadays we prefer to speak of epiceno nouns, because in reality they are words that are either masculine or feminine (or even in some cases common).
http://www.wikilengua.org/index.php/Gรฉnero_gramatical
1.1 Male gender
They are masculine words:
Most words that end in -o. They also have masculine gender other words that end in other letters, such as a, e.
The rivers, mountains, volcanoes, isthmus, channels: the Nile, the Amazon, the Himalayas, the Aneto, the Etna.
Cyclones, including hurricanes, typhoons and tropical storms: the Gustav, the Hanna.
The months and the days of the week: It was a very cold August, the flowery and beautiful May.
Most winds (except breeze and tramontana).
The musical notes: the, the flat.
The augmentatives in -on applied to things, even if they derive from feminine words: the inn, the notion.
Journals (in Spain): Week, Clara, Research and science.
The names of the cardinal points: north, south, east, east or west, west, sunset or west.
The numbers: three, five, 93.
1.2 Female gender
They are feminine words:
Most words that end in a. They also have feminine gender other words that end in other letters, such as o, e.
The letters: the hache, the o.
The words ending in -dad, -tad, -ciรณn, -sion: the freedom, the lesson, the city, etc. (except for augmentative derivatives, such as notices, and some exceptional cases).
There are finished names in which they are, already masculine, already feminine, according to the sense in which they are used. Barba, for example, is feminine when it means the part of the human body so called; and it is masculine when it denotes the actor who represents the roles of an elder. Cure, priest, is masculine, and feminine in the other meanings. Comet is masculine as a celestial body, and feminine as a toy for boys. Crisma, in serious style is masculine, and feminine in vulgar.