The Collaborative International Dictionary of English v.0.48:

Vinegary \Vin"e*gar*y\, a.
   Having the nature of vinegar; sour; unamiable.
   [1913 Webster]

WordNet (r) 3.0 (2006):

vinegary
    adj 1: tasting or smelling like vinegar [syn: acetose,
           acetous, vinegary, vinegarish]
    2: having a sour disposition; ill-tempered [syn: vinegary,
       vinegarish]