Definition of "Twin" :

noun: a duplicate copy

noun: a waterfall in the Snake River in southern Idaho

noun: (astrology) a person who is born while the sun is in Gemini

noun: either of two offspring born at the same time from the same pregnancy

verb: give birth to twins

verb: grow as twins

"Twin crystals."

verb: bring two objects, ideas, or people together

verb: duplicate or match

"The polished surface twinned his face and chest in reverse."

adjective: being two identical