1. noun
a) A major language family which includes many of the native languages of Europe, Western Asia and India, with notable Indic, Iranian and European sub-branches.
See Also: PIE
2. adjective
a) Of or related to the languages originally spoken in Europe and Western Asia.
b) Of or related to the hypothetical parent language of the Indo-European language family. Also called Proto-Indo-European and abbreviated PIE.
Wikipedia foundation.