underpromote

verb2

1. •
   To promote inadequately.

   • It was a teen party sponsored by the hip-hop radio station Hot 97 (WQHT-FM), and maybe an underpromoted one: much of the room was empty. — 2009
2. •
   To promote (a pawn that has crossed the board) to a less powerful piece than a queen, which is sometimes strategically useful.