adverb
mercilessly; relentlessly; without mercy
Used when someone acts without leniency, pity, or restraint; often describes harsh criticism, strict enforcement, or unrelenting natural forces.
See also: 容赦
上司はミスを容赦なく指摘した。
The boss mercilessly pointed out the mistakes.
太陽が容赦なく照りつけている。
The sun is beating down relentlessly.
Adverbial form of 容赦 (mercy, pardon) with the negative なく, literally 'without mercy'. 容赦 is a Sino-Japanese compound of 容 (accept, tolerate) and 赦 (pardon, forgive).