Source : Webster's Revised Unabridged Dictionary (1913)

Tepid \Tep"id\, a. [L. tepidus, fr. tepere to be warm; akin to
   Skr. tap to be warm, tapas heat.]
   Moderately warm; lukewarm; as, a tepid bath; tepid rays;
   tepid vapors. -- {Tep"id*ness}, n.

Source : WordNet®

tepid
     adj : moderately warm; "he hates lukewarm coffee"; "tepid bath
           water" [syn: {lukewarm}]