The phonological word, or prosodic word (commonly shortened to pword, PrWd, or symbolised as ÃÂ) is a unit in the phonological hierarchy of words. It is often larger than a syllable, but lower than an intonational phrase. A phonological word could be a bare root, a root and its affixes, or even in some cases a compound word.
Prosodic words can be identified by domain markers: non-linguistic or phonological signs that a speaker has reached the beginning or end of a prosodic word. Examples of domain markers could be word-final devoicing or vowel harmony.
In more formal terms, a prosodic word can be described as a prosodic domain in which phonological features within the same lexical unit may spread from one morpheme to another.
Functional words like adpositions tend to be phonologically weak, and, as a result, they often combine to become a part of a larger prosodic word with their lexical hosts. This is common cross-linguistically.
A prosodic word in sign languages can consist of a monosyllabic sign. A monosyllabic sign can be repeated, resulting in a larger prosodic word. Domain markers in sign languages can include mouthing corresponding spoken words, pointing, or head tilting.
The phonological word and grammatical word are not equivalent. What counts as a word for the phonology can be either smaller or larger than what counts as a word for syntactic purposes. A clear case of this mismatch is compound words, which count as two words phonologically, but one in the syntax.