na-adjective, noun
inactive; sluggish; dull; quiet
Describes a lack of activity, energy, or liveliness in people, animals, markets, or natural phenomena. Often used in formal or written contexts.
今日の市場は不活発だった。
Today's market was sluggish.
彼は病気の後、しばらく不活発な生
After his illness, he led an inactive life for a while.
Compound of 不 (fu-, 'not') + 活発 (kappatsu, 'active, lively'). The kanji 活発 is a standard Sino-Japanese word meaning 'activity' or 'liveliness'.