1. Being in effect or operation
   "bus service is in operation during the emergency"
   - operational, operating

See also: operative

• hawsehole
• hawsepipe
• hawser
• hawser bend
• hawthorn
• Hawthorne
• hay
• hay bacillus
• hay bale
• hay conditioner
• hay fever
• hay-scented
• hay-scented fern
• Hayastan
• haycock
• Haydn
• Hayek
• Hayes
• hayfield
• hayfork
• haying
• haying time
• hayloft
• Haym Salomon
• haymaker