Definitions

A word is clitic iff it has syntactic - and typically also phonotactic - properties of a word but forms a phonological word with another grammatical word, its host, which bears the stress if the phonological word receives it. The principal criteria of its being phonologically bound to its host are:

• having no stress of its own
• and being subject to sandhi rules.

A clitic is a clitic word. Clisis is the property or process of something being or becoming clitic.

• A clitic that precedes its host is proclitic.
• A clitic that follows its host is enclitic.

The clitics in – are enclitic; the ones of are proclitic. It is possible for a word to be enclitic in one construction and proclitic in another. There is also a subtype of enclitics that may start a sentence.

A clitic may be internal to a word form and is then endoclitic. Port. começa-lo-ei (begin-OBJ.3.SG.M-FUT.1.SG) ‘I will start it’ is an example. It is also possible that the syntagmatic position of a clitic relative to other bound morphs in the complex varies. In all of these cases, the diachronic perspective reveals the peripheral morph which appears to be an affix to stem from a word, too, which either got attached to the clitic complex or is itself the former host of the clitic.

The host of a clitic is the word form with which it forms a phonological word. This may differ from its syntactic coconstituent. In several languages, pronouns are enclitic to whatever precedes them, although they syntactically depend on the constituent immediately following them. German has portmanteau forms consisting of a prepositions plus the following definite article, as in am Abend (at-DEF.M.SG.DAT evening) ‘in the evening’, where the article is enclitic although it bears no syntactic relation to the preposition and, instead, to the nominal expression following it.

Phenomenology

Clitics may be subdivided by the criterion of a systematic, paradigmatic or supra-paradigmatic, relation born to non-clitic (= tonic) words of like function:

1) A clitic word may be unstressable and lack a tonic counterpart. This means that it cannot, in its given segmental form and syntagmatic position, receive sentence stress while keeping its meaning. Several German modal particles are of this kind (other examples include the Latin conjunction -que ‘and’ and the English genitive 's).

Both modal particles eben and ja are unstressable. (If ja in is stressed, this means it is replaced by its non-clitic homograph, which in colloquial German is used to affirmatively contradict the interlocutor.¹)

2) A clitic may have a tonic alternant. Some languages have clitic pronouns which are phonologically reduced or allegro forms of tonic pronouns. This is, again, so in German (and in English, too).

Versions #a and #b of are fully synonymous. The personal pronouns in direct object function keep their syntagmatic position whether clitic or tonic. The full forms of the #a version may or may not have sentence stress.² The clitic variants of the #b version cannot be stressed. Such clitics may be called simple clitics (with Zwicky 1977:6).

3) Case #2 is to be distinguished from the coexistence of two paradigms of pronouns or pronominal indexes in a language system. French is among the languages which have a set of tonic and a set of clitic pronouns. In colloquial French, coreferential pronouns of either paradigm can cooccur in a clause, as in .

Such clitics differ from simple clitics in that the two paradigms of pronominal forms belong to different distribution classes. Thus, the clitic pronoun is not an alternant of the tonic one. Such clitics may be called special clitics (with Zwicky 1977:6).

Clitics and particles

Clitics are occasionally confused or lumped together with particles. These two categories do not even share an immediate hyperonym, which means they are unrelated:

• A clitic may be an inflecting word (.b) or a particle (f).
• A particle may be clitic (f) or non-clitic (stressed, like the ja of fn. 2).

Clitic vs. affix

By contrast, clitics are sometimes not easily distinguished from affixes. In principle, the difference is categorial:

• A clitic is a word and possibly even an inflected word form.
• An affix is a bound form and by definition monomorphemic.

However, since a clitic lacks stress, it is not a free form (it cannot constitute an utterance), and in this it resembles an affix. Moreover, many clitics are monomorphemic like affixes.

Clitics differ from affixes in the following respects:

1. An affix can be stressed (like the future conjugation endings of Romance) or stressless (like the present conjugation endings of Romance); clitics are unstressed.
2. A clitic may have a syntagmatic position which is insensitive to the category of its host. This “promiscuous host selection” is due to the fact that the position of a clitic is often a higher-level syntactic position. In particular:
   1. The clitic may be adjacent to a syntagma of a certain category, no matter what the category of the particular subconstituent of that syntagma is that the clitic happens to be adjacent to. This is the case, e.g., of the English genitive 's, as in the man we met yesterday's son.
   2. The position of the clitic may be defined with respect to a clause boundary, typically either following the first syntactic constituent or phonological word (called “Wackernagel's position”) or preceding the final clause boundary (this is frequent for sentence-type particles).
   By contrast, an affix selects a host of a certain category.
3. The boundary between an affix and its host is weaker (and the bond is tighter) than the boundary between a clitic and its host. As a consequence, phonological processes whose domain is the phonological word may differ for clitics and for affixes. In principle, a clitic is less subject to such processes – undergoes less phonological adaptations – than a clitic. In the most straightforward case, an affix undergoes internal sandhi, a clitic does not and may instead undergo external sandhi.
4. An affix attaches to a stem, a clitic attaches to a word form. As a consequence, a clitic may follow an affix; but an affix of the host cannot follow a clitic (although the clitic may, of course, have an affix of its own).
5. In general, the order of both affixes and clitics may obey a template rather than scope. However, the order of affixes is fixed, while the order of clitics may be variable.

¹ Sie ist já ein Genie is a possible answer to Sie ist kein Genie ‘She is not a genius.’

² the neuter pronoun only under very peculiar circumstances; but that is a different story

Zwicky, Arnold M. 1977, On clitics. Bloomington, IN: Indiana University Linguistics Club.