1. With passionate fervour
   - fierily, fervently

See also: fervid

• underskirt
• underslung
• undersoil
• underspend
• understaffed
• understand
• understandability
• understandable
• understandably
• understanding
• understandingly
• understate
• understated
• understatement
• understock
• understood
• understrength
• understructure
• understudy
• undersurface
• undertake
• undertaker
• undertaking
• underthings
• undertide