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"harden" is also used as a crossword clue. If that's what you saw, the answer is often set (3 letters).
Definitions
cause to accept or become hardened to; habituate
Word origin
From Middle English hardenen, equivalent to hard + -en. Cognate with Danish hærdne (“to harden; cure”), Swedish hårdna (“to harden”), Norwegian herdne (“to harden”), Icelandic harðna (“to harden”).
Used in a sentence
“The Chief Medical Officer of London Transport believes that public opinion against smoking will harden to the point of a total bar on the Underground, as in other countries.”
“When thou goest to return into Egypt, see that thou do all those wonders before Pharaoh, which I have put in thine hand: but I will harden his heart, that he shall not let the people go.”
“He hardened as he imagined himself running his hands over her small breasts”
Source: Wiktionary, CC BY-SA 4.0
Used as a crossword answer1 curated clues
01“Make tough”6 letters
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