Morphology

There are several difficulties in arriving at a consistent use of the term "word" in relation to other categories of linguistic description, and several criteria have been suggested for the identification of words in a language. In the UNLarium, words (aka word forms) are "the physically definable units which one encounters in a stretch of writing (bounded by spaces) or speech (where identification is more difficult, but where there may be phonological clues to identify boundaries, such as a pause, or juncture features)" (Crystal, 2008, p. 522).

In synthetic (inflected) languages, such as the Indo-European ones, we often recognize a sort of "word unit" under a number of different word forms: "loves", "loving" and "loved", for instance, are not usually considered to be different words, but different forms of the same word ("love"). This underlying word unit is often referred to as a lexeme, which corresponds therefore to a set of forms taken by a single word.

The different instances of a lexeme are said to be derived from different morphological structures, which means that word forms are analysed into smaller units, called “morphemes”. A morpheme is the smallest linguistic unit that has semantic meaning.

There are two main different types of morphemes:

• root (ROO) - The root is the primary unit of a word unit, which carries the most significant aspects of semantic content. Words may have one (“fire”, “man”, “round”, “table”, “blue”, “green”) or several roots, either concatenated (“fireman”) or separated by hyphen (“blue-green”) or spaces (“round table”);
• affix (AFX) - The affix is a morpheme attached to the root to modify its meaning.

Affixes are divided into several categories, depending on their position and their role with reference to the root. The most important positional categories are:

• prefix (PFX) - Appears at the front of the root (such as "un" in "undo", or "re" in "rewrite")
• suffix (SFX) - Appears at the back of the root (such "s" in "tables", or "er" in "writer")
• infix (IFX) - Appears within the root (very rare in English, such as "ma" in "sophistimacated")
• circumfix (CCX) - Appears at the front and at the back of the root (such as "a" + "ed" in "ascattered")

As for their roles, there are two main different types of affixes:

• inflectional affix (IAX) - Assign grammatical properties (such as number, gender, tense, person) to the root in order to form the different word forms of the same lexeme ("s" in "tables", "ed" in "loved", etc)
• derivational affix (DAX) - Form a new lexeme by modifying the meaning (and sometimes the category) of the root ("un" in "unhappy", "ness" in "happiness").

Word forms (WFO) are, therefore, the combination of ROOTS + INFLECTIONAL AFFIXES + DERIVATIONAL AFFIXES. The combination of ROOTS + DERIVATIONAL AFFIXES (i.e., word forms without inflectional affixes) is normally referred to as stem or inflectional root.

Lexemes, as a set of different word forms with different inflectional affixes, but with the same stem, are normally referred to by a citation (default) form called lemma. The lemma, more generally referred to as headword, is essentially an abstract representation, subsuming all the formal lexical variations which may apply within the same lexeme. It is the word form which occurs at the beginning of a dictionary entry, and which is normally the singular, for nouns; the masculine singular, for adjectives; and the infinitive, for verbs. The lemma frequently coincides with the stem, but it is not always the same. In Spanish, for instance, the adjective "hermoso" (= beautiful) has "hermos-" as the stem (the suffix "o" indicates masculine gender) and "hermoso" (which is the "unmarked" form) as the lemma.

Examples

lexeme	word forms	root	derivational affixes	inflectional affixes	stem	lemma
1	here	here			here	here
2	happy	happy			happy	happy
3	unhappy	happy	un-		unhappy	unhappy
4	table, tables	table		-s	table	table
5	happiness	happy	-ness		happiness	happiness
6	love, loves, loving, loved	love		-s, -ing, -ed	love	love
7	hermoso, hermosa, hermosos, hermosas (es = beautiful)	hermos-		-o, -a, -s	hermos-	hermoso
8	unbreakableness	break	un-, -ness		unbreakableness	unbreakableness
9	fireman, firemen	fire, man			fireman	fireman
10	part of speech, parts of speech	part, of, speech		-s	part of speech	part of speech