Definitions

1. adjective

most sorrowful or dejected; most inclined to mope.

“He was the mopeiest person at the party, and his mood quickly dampened the atmosphere.”

2. superlative form of ‘mopey’

used to compare three or more things, with the one being the most sorrowful or dejected.

“She was the mopeiest of the three friends, always complaining about something.”