a language learned by a person after his or her native language, especially as a resident of an area where it is in general use.
a language widely used, especially in educational and governmental functions in a region where all or most of its speakers are nonnative, as English in India or Nigeria.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
a language other than the mother tongue that a person or community uses for public communication, esp in trade, higher education, and administration
a non-native language officially recognized and adopted in a multilingual country as a means of public communication
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012