1. Not closed or secured
   "the car door was unfastened"; "unfastened seatbelts" 
2. Affording unobstructed entrance and exit; not shut or closed
   - open 
3. Not buttoned
   - unbuttoned 
4. Not tied
   - untied

1. Cause to become undone
   "unfasten your belt" 
2. Become undone or untied
   "The shoelaces unfastened"

See also: ajar, open, open-collared, unbarred, unbolted, undone, unfastener, unfastening, unlatched, unlocked, unsecured, wide-open

Type of: open, open up, undo

Antonym: fasten, fastened

• genus Pellaea
• genus Pellicularia
• genus Peltandra
• genus Peltiphyllum
• genus Penelope
• genus Peneus
• genus Penicillium
• genus Pennatula
• genus Pennisetum
• genus Penstemon
• genus Peperomia
• genus Perca
• genus Percina
• genus Perdix
• genus Pereskia
• genus Pericallis
• genus Peridinium
• genus Perilla
• genus Periophthalmus
• genus Peripatopsis
• genus Peripatus
• genus Periplaneta
• genus Periploca
• genus Perisoreus
• genus Peristedion