insipid

modif.

1. Tasteless

   flat, stale, vapid; see tasteless 1.

2. Uninteresting

   vapid, flat, banal, weak, lifeless, characterless; see also dull 4.

insipid implies a lack of taste or flavor and is, hence, figuratively applied to anything that is lifeless, dull, etc. insipid table talk; vapid and flat apply to that which once had, but has since lost, freshness, sharpness, tang, zest, etc. the vapid, or flat, epigrams that had once so delighted him; banal is used of that which is so trite or hackneyed as to seem highly vapid or flat her banal compliments