a suffix forming nouns or adjectives, sometimes a diminutive of the base word and usually confined to informal and jocular use (bitsy; footsie; halvsies); adjectives formed with -sy, may be ironic, implying that the quality in question is self-consciously assumed or feigned (artsy; cutesy; folksy). The combination of -s3. and -y1. or -y2. in certain words (antsy; gutsy) should perhaps be considered further instances of this suffix.
Origin of -sy
perhaps orig. two distinct suffixes, one diminutive (as in Betsy, popsy, tootsy) and the other adjectival; sources of both are uncertain