This is the 9765th most frequent Japanese word.
虚し
"虚し" (むなし, munashi) means "empty" or "vain," often referring to feelings of void or futility.
虚しく is used as an adverb here, expressing a state of emptiness or futility.
人生の意味を見失うと、とても虚しくなる。
If you lose sight of the meaning of life, you become very empty.
空虚な is an adjective describing a feeling or state of emptiness.
空虚な気持ちは時として人を成長させる。
A sense of emptiness can sometimes lead to personal growth.
虚しい is an adjective conveying the meaning of being hollow or insubstantial.