Describes a person, attitude, or work that rejects conventional values and beliefs, often with a cold or cynical tone. Related to ニヒリスティック.
from Latin nihil
See also: ニヒリスティック
His nihilistic way of laughing was striking.
A nihilistic worldview pervades that novel.
He gave a cynical smile and said nothing.
He always takes a cynical, aloof attitude that confuses those around him.
The protagonist walked away with a cynical smile.
楽観的 describes a hopeful, positive outlook, the opposite of the cold, meaning-rejecting attitude conveyed by ニヒル.
From Latin 'nihil' (nothing), via German or English influence. The exact path into Japanese is uncertain, but it is used as a na-adjective meaning 'nihilistic'.