

明日は仕事がオフなので、ゆっくり休みます。
会議中は携帯の電源をオフにしてください。
今度のオフの日、一緒に買い物に行かない?
"オフ" is in the lesson "Adjectives 6" (Level 40), along with 10 other useful words. LinDuo has 180 topic lessons like this one, 2,379 words in total. Every word has an illustration, a transcription and pronunciation in a female and a male voice. Just 10–15 minutes a day is enough to learn them all. Free, and works offline.