Basic Details
Word: Convexity
Part of Speech: Noun
Meaning: The state of curving outwards, like the outside of a ball or the back of a spoon.
Synonyms: bulge, roundness, curvature
Antonyms: concavity
How to Spell Convexity
Syllables: con - vex - i - ty
Tricky part: Convex ends with an x, not ks or cs, and the noun ending is -ity.
Watch out for: convexety, conveksity, convecsity, convexaty
Memory tip: A concave surface caves in, like the inside of a cave. Its partner, convex, bulges out. Add -ity to convex and you have the noun.
Usage Examples
Example 1: The slight convexity of the road lets rainwater run off to the sides.
Example 2: You can see the convexity of the dome from across the river.
Example 3: Mr Bose drew the convexity of the mirror on the board with a curved line.
Fun Fact
Many car wing mirrors are convex so that they show a wider view of the road behind; that is why some carry the warning that objects are closer than they appear.
Practise the CREST Way
Spell-o-Spell
Three of these words are spelt correctly. Choose the meaning of the misspelt word:
1. perpendicular 2. symmetry 3. convexaty 4. circumference
a) at an angle of 90 degrees to a line
b) the quality of curving outwards
c) an exact match between two halves
d) the distance around a circle
Show answer
b) the quality of curving outwards. Symmetry, perpendicular and circumference are correct, and convexity ends in -ity, not -aty.
Word Connection
Choose the antonym of the word convexity as used in the sentence:
The convexity of the glass makes the letters look larger when you hold it over the page.
a) roundness
b) bulge
c) concavity
d) curvature
Show answer
c) concavity. Roundness, bulge and curvature describe an outward curve; concavity curves inwards.
Word Cookie
Find the extra letter in the word:
convexxity
a) i
b) x
c) t
d) v
Show answer
b) x. Convex has only one x; x already stands for two sounds, k and s, so it never needs doubling here.
Multiple Choice Questions
1. Which object shows convexity?
a) a sheet of paper
b) a flat steel ruler
c) the back of a spoon
d) the inside of a bowl
Show answer
c) the back of a spoon
2. A lens that is thicker in the middle than at its edges is called ____.
a) plane
b) convex
c) hollow
d) concave
Show answer
b) convex
