na-adjective
sarcastic; derisive; sneering
Describes an attitude or remark that is coldly mocking or scornful. Often used with 態度, 口調, or 笑い.
彼の冷笑的な態度が気に入らなかった。
I didn't like his sarcastic attitude.
彼女は冷笑的な口調
She answered in a derisive tone.
嘲笑 is a noun or suru-verb for open ridicule or scorn. 冷笑的 is more about a sneering, contemptuous manner rather than direct mockery.
Compound of 冷笑 (cold laugh, sneer) + 的 (suffix forming adjectival nouns). The exact historical derivation is uncertain, but the word follows a common pattern for creating descriptive terms from Sino-Japanese roots.