1. Of a stimulus just strong enough to be consciously experienced 
2. At a threshold or transitional stage

Encyclopedia: Liminal

• unfavourableness
• unfavourably
• unfazed
• unfearing
• unfeasibility
• unfeasible
• unfeathered
• unfed
• unfeeling
• unfeelingly
• unfeelingness
• unfeigned
• unfeignedly
• unfeminine
• unfenced
• unfermented
• unfertile
• unfertilised
• unfertilized
• unfetter
• unfettered
• unfilial
• unfilled
• unfilmed
• unfinished