Folly and foolishness denote a want of mental and often of moral balance. Fatuity is sometimes used as equivalent to idiocy, but more frequently signifies conceited and excessive foolishness or folly.

J. C. Fernald, English Synonyms and Antonyms (1914)

Example sentences

stupidity There's a fine line between bravery and stupidity.
folly Who lives without folly is not so wise as he thinks.
absurdity The absurdity of the situation was almost comical.

Popularity over time

Word	1850 → 2019	Trend
foolishness		rising
stupidity		rising
folly		steady
absurdity		steady
imbecility		falling

Use in printed books, per decade from 1850 to 2019.

By length

4 letters: bull¹
5 letters: folly², fudge¹
6 letters: idiocy⁴, lunacy³, drivel²
7 letters: madness², rubbish², prattle², foolery³, fatuity
8 letters: unwisdom
9 letters: stupidity⁴, absurdity⁴, craziness³, silliness³
10 letters: ineptitude⁴, triviality⁵, imprudence³, balderdash³, imbecility, unwiseness
11 letters: shallowness³
12 letters: extravagance⁴, indiscretion⁴
13 letters: irrationality⁶, senselessness
14 letters: ridiculousness

The small number after each word is its number of syllables (folly² = 2 syllables).

In other languages

Français: bêtise
Italiano: dabbenaggine
Español: tontería
Deutsch: Dummheit
Català: brutícia