doldrums /dolˈdrəmz/

1. Those parts of the ocean near the equator where calms and baffling winds prevail (nautical)
2. A state of inactivity or stagnation
3. Low spirits

• undemonstrative
• undemonstrativeness
• undeniable
• undeniableness
• undeniablenesses
• undeniably
• undenominational
• undenominationalism
• undependable
• undependableness
• undepending
• undeplored
• undepraved
• undepreciated
• undepressed
• undeprived
• under
• under-
• underachieve
• underachieved
• underachievement
• underachiever
• underachievers
• underachieves
• underachieving