periodontology/ˌperi·ədonʹtoləji/ noun

• active service
• active transport
• activist
• activity
• act of God
• act one's age
• actor
• act out
• act/play the fool
• actress
• actual
• actual bodily harm
• actualise
• actuality
• actualize
• actually
• actuary
• actuate
• act up
• acuity
• aculeate
• acumen
• acuminate
• acupoint
• acupressure