1A fluorescent lamp — a lighting fixture using a fluorescent tube, commonly used in offices and homes.
キッチンの蛍光灯が切れたので、新しいのに交換した。
The fluorescent light in the kitchen burned out, so I replaced it with a new one.
教室の蛍光灯がジージーと音を立てている。
The fluorescent light in the classroom is buzzing.
最近はLED照明が普及して、蛍光灯を見る機会が減った。
Recently, LED lighting has become common, and fluorescent lamps are seen less often.
2(dated slang, rarely used today) A person who is slow to react — the term likens them to the delay before old-style fluorescent lamps would light up.