noun
chain smoker
A person who smokes cigarettes continuously, lighting a new one from the previous one. Loanword from English; used in casual and neutral contexts.
彼はチェーンスモーカーで、一日に三箱吸う。
He is a chain smoker and smokes three packs a day.
Variant with interpunct; less common but still encountered.
ヘビースモーカー means 'heavy smoker' and emphasizes the quantity smoked, while チェーンスモーカー specifically refers to the habit of lighting one cigarette after another.
Loanword from English 'chain smoker'.