(mathematics) a root (as in a square root) / (linguistics) an etymological root / (music) root note in a chord

acre (unit of surface area)

arena (an enclosed area, often outdoor)

Albany

al-Qaeda

A transliteration of the English male given name Albert

barbell (wide steel bar with premeasured weights)

(rare) buzzword

burner (element on a kitchen stove)

base (bottom, foundation) / base (something on which something else rests) / (baseball) base