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

See also: operative

• derived function
• deriving
• derma
• dermabrasion
• Dermacentor
• Dermacentor variabilis
• dermal
• Dermaptera
• dermatitis
• Dermatobia
• Dermatobia hominis
• dermatoglyphic
• dermatoglyphics
• dermatologic
• dermatological
• dermatologist
• dermatology
• dermatome
• dermatomycosis
• dermatomyositis
• dermatophyte
• dermatophytosis
• dermatosclerosis
• dermatosis
• Dermestidae