The Collaborative International Dictionary of English v.0.48:
Subacid \Sub*ac"id\, a. [L. subacidus. See Sub-, Acid.] Moderately acid or sour; as, some plants have subacid juices. -- n. A substance moderately acid. [1913 Webster]WordNet (r) 3.0 (2006):
subacid adj 1: slightly sour to the taste