quatercentenary/ˌkwatəsenʹteenəri, -ʹtenəri/ noun (pl -ies) (pl quatercentenaries)

• at first blush
• at first glance
• at first hand
• at first/second hand
• at first sight
• (at) full pelt
• at full stretch
• at gunpoint
• Athabaskan
• at hack
• Athanasian Creed
• at hand
• Athapaskan
• atheism
• atheling
• athematic
• athenaeum
• Athenian
• atheroma
• atherosclerosis
• at His/Her Majesty's pleasure
• athlete
• athlete's foot
• athletic
• athletics