a

**:**a point of transition (as from one historical period to the next)

**:**turning point

b

**:**either horn of a crescent moon

c

**:**a fixed point on a mathematical curve at which a point tracing the curve would exactly reverse its direction of motion

d

**:**an ornamental pointed projection formed by or arising from the intersection of two arcs or foils (see foil entry 2 sense 4)

e(1)

**:**a point on the grinding surface of a tooth

(2)

**:**a fold or flap of a cardiac valve

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Merriam-Webster unabridged
## Share