公共汽车(gōng gòng qì chē) - bus in Mandarin

公共汽车 (gōnggòng qìchē) is the full, formal word for "bus". 公共 (gōnggòng) means "public" and 汽车 (qìchē) means "car, motor vehicle", so it reads literally as "public motor vehicle", the everyday city bus rather than a coach.

In speech, most people shorten it to just 公交车 (gōngjiāochē) or even 公交 (gōngjiāo) on the mainland, while Taiwan tends to say 公車 (gōngchē). 公共汽车 (gōnggòng qìchē) is the word you will see written out in full on signs, timetables and in textbooks, so it is worth knowing even though nobody says all four syllables in casual conversation.

Ride it with 坐 (zuò), "to sit, to take (transport)": 坐公共汽车 (zuò gōnggòng qìchē), "to take the bus", never 骑 (qí), which is reserved for things you straddle, like a bike or a motorbike.