U-boat /ūˈbōt or (German) ooˈ/

A German submarine

• groundbreaking
• groundbreakings
• groundburst
• groundbursts
• ground cherries
• ground cherry
• ground control
• ground controller
• ground controllers
• ground controls
• ground cover
• ground covers
• ground crew
• ground crews
• ground-cuckoo
• ground-cuckoos
• ground-dove
• ground-doves
• grounded
• groundedly
• ground effect
• ground effects
• ground elder
• grounden
• grounder