merciless
[adjective]
Synonyms: cruel, barbarous, callous, hard-hearted, harsh, heartless, pitiless, ruthless, unforgiving

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Antonyms: merciful
Contrasted words: charitable, lenient, tolerant, easy, easygoing
Related Words: compassionless, cutthroat, pitiless, gratuitous, uncalled-for, wanton

[TahlilGaran] English Synonym Dictionary ▲

mer‧ci‧less /ˈmɜːsɪləs $ ˈmɜːr-/ adjective

1. cruel and showing no kindness or forgiveness:
a merciless attack
a merciless killer

2. merciless heat/cold/wind etc heat, cold etc that is very great or strong and unpleasant, and does not stop:
It brings some relief from the merciless summer heat.
—mercilessly adverb:
He teased his sister mercilessly.

[TahlilGaran] Dictionary of Contemporary English ▲