The Collaborative International Dictionary of English v.0.48:

Locution \Lo*cu"tion\ (l[-o]*k[=u]"sh[u^]n), n. [L. locutio, fr.
   loqui to speak: cf. F. locution. ]
   Speech or discourse; a phrase; a form or mode of expression.
   " Stumbling locutions." --G. Eliot.
   [1913 Webster]

         I hate these figures in locution,
         These about phrases forced by ceremony.  --Marston.
   [1913 Webster]

WordNet (r) 3.0 (2006):

locution
    n 1: a word or phrase that particular people use in particular
         situations; "pardon the expression" [syn: saying,
         expression, locution]