cusp

noun

ˈkəsp 

: point, apex: such as

a

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

also : edge, verge

on the cusp of stardom

… you're on the cusp between heat exhaustion and life-threatening heatstroke.

—Mark Jannot

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

cuspate

ˈkə-ˌspāt 

-spət

adjective

cusped

ˈkəspt 

adjective

Illustration of cusp

• 1 cusp d

Synonyms of cusp

• verge
• brink

Examples of cusp in a Sentence

the cusp of a tooth

medical researchers who are on the cusp of a major breakthrough

Recent Examples on the Web

Stock market bulls wrestled back control last week after a brief respite, putting the S & P 500 back on the cusp of another record high. —Morgan Chittum, CNBC, 23 May 2026

Five players in the Game 1 lineup reached the Stanley Cup Final with the Canadiens in 2021, the precursor to this rebuild that has led them back to the cusp of that stage. —Sean Gentille, New York Times, 23 May 2026

While Penta has been very good as champion and remains a wildly popular star, WWE desperately needs some fresh faces working on the cusp of the main event scene. —Blake Oestriecher, Forbes.com, 23 May 2026

The Hurricanes are one half of an Eastern Conference finals that has seen its teams take very different paths to the cusp of reaching the Stanley Cup final. —Andrew Greif, NBC news, 20 May 2026

Word History

Etymology

Latin cuspis point

First Known Use

1585, in the meaning defined above

Phrases Containing cusp

• on the cusp

Kids Definition

cusp

noun

ˈkəsp 

: a point or pointed end or part: as

a

: either of the pointed ends of a crescent moon

b

: a point on the grinding surface of a tooth

c

: a fold or flap of a heart valve

Medical Definition

cusp

noun

ˈkəsp 

1

: a point on the grinding surface of a tooth

2

: a fold or flap of a cardiac valve

cuspal

ˈkəs-pəl 

adjective