Noun
(uncountable) The state or quality of being unkind.
(countable) An unkind act.
(countable) The collective noun for ravens
Source: en.wiktionary.orgDeeds that seemed unimportant at the time would prove to have been momentous; a tiny act of selfishness and unkindness or, conversely, an unconsidered act of generosity would become the measure of a human life. Karen Armstrong
Unkindness may do much, And his unkindness may defeat my life, But never taint my love. William Shakespeare
Ignorant kindness may have the effect of cruelty; but to be angry with it as if it were direct cruelty would be an ignorant unkindness. George Eliot
So you think that you could save him, And we know that someone died. Oh, an unkindness of ravens, And we know that Mary lied. Courtney Love
Come, gentlemen, I hope we shall drink down all unkindness. William Shakespeare
It is easy to forget a kindness, but one remembers unkindness. Hindi Proverb