Dictionary:

syntagma

  (sĭn-tăg'mə) also syntagm (sĭn'tăm)

1. A sequence of linguistic units in a syntagmatic relationship to one another.
2. A sequence of words in a particular syntactic relationship to one another; a construction.

[New Latin, from French syntagme, from Greek suntagma, suntagmat-, arrangement, syntactic unit, from suntassein, suntag-, to put in order. See syntax.]

syntagm [sin‐tam] or syntagma [sin‐tag‐mă], a linguistic term designating any combination of units (usually words or phonemes) which are arranged in a significant sequence. A sentence is a syntagm of words. Language is said to have two distinct dimensions: the syntagmatic or ‘horizontal’ axis of combination in which sequences of words are formed by combining them in a recognized order, and the paradigmatic or ‘vertical’ axis of selection, from which particular words are chosen to fill given functions within the sequence. The syntagmatic dimension is therefore the ‘linear’ aspect of language. See also syntax.

The noun has one meaning:

Meaning #1: a syntactic string that forms a part of some larger syntactic unit
  Synonym: syntagm