1to use anywhere, anytime (card, ticket etc)
2to be used by everyone (language, textbook etc)
3(of two or more things) interchangeable
Example
yīng yǔ英语xiàn现yǐ已chéng wéi成为shì jiè世界shàng上xǔ duō许多guó jiā国家de的tōng yòng通用yǔ yán语言liǎo了。
英语现已成为世界上许多国家的通用语言了。
English has now become the common language of several nations in the world.