"Either" is a conjunction. More specifically, it is a correlative conjunction.
It is a pronoun -- either interrogative or relative.
The word "brief", depending on context, can be either a verb, a noun, or an adjective.
The part of speech that the word my is used as is an adjective.
It can be either a noun or an adjective, depending upon its use in a sentence.
A suffix changes a word's part of speech. For example, the word 'happy' is an adjective. But when you add a suffix, which is an ending, it can change the part of speech. Happily is an adverb. Happiness is a noun.
It is a pronoun -- either interrogative or relative.
The word "initial" can function as either an adjective or a noun.
"Fear" can be either a noun or a verb.
The word "brief", depending on context, can be either a verb, a noun, or an adjective.
The word "sympathetic" can function as either an adjective or a noun.
The word "defense" can function as either a noun or a verb.
Noun
Caption can be either a noun (object) or a verb (action).
The word "constraint" is a noun. The word "design" can be either a noun or a verb but in this context it is a noun.
The word "constraint" is a noun. The word "design" can be either a noun or a verb but in this context it is a noun.
The word "stigma" can function as either a noun or a verb, depending on how it is used in a sentence.
The word "practiced" can function as either a past tense verb or an adjective in a sentence.