An affix (in modern sense) is a morpheme that is attached to a word stem to form a new word. Affixes may be derivational, like English-ness and pre- , or inflectional, like English plural-s and past tense-ed.They are bound morphemes by definition; prefixes and suffixes may be separable affixes.Affixation is, thus, the linguistic process speakers use to form different words by adding morphemes (affixes) at the beginning (prefixation), the middle (infixation) or the end (suffixation) of words.exical affixes (or semantic affixes) are bound elements that appear as affixes, but function as incorporated nouns within verbs and as elements of compound nouns. In other words, they are similar to word roots/stems in function but similar to affixes in form.