Jaylee asks whether the plural endings -s and -es are considered suffixes.
The short answer is yes.
A suffix is a letter or group of letters added to the end of a word or root to change the word. A suffix can change the part of speech, as in these examples:
exist (verb) + ence = existence (noun)
wire (noun) + less = wireless (adjective)
or form the plural of a noun:
college (singular noun) + s = colleges (plural noun)
or change the tense of a verb:
elect (present tense) + ed = elected (past tense)
Because of the way meanings evolve over time, a word + suffix combination can have a meaning that is very different from the meaning of the word without the suffix, as in this example:
organ (a noun meaning "a part of the body") + ize = organize (a verb meaning "arrange or plan")