Pronunciation: (in'tOO; unstressed in'too, -tu),[key] —prep. 1. to the inside of; in toward: He walked into the room. The train chugged into the station. 2. toward or in the direction of: going into town. 3. to a point of contact with; against: backed into a parked car. 4. (used to indicate insertion or immersion in): plugged into the socket. 5. (used to indicate entry, inclusion, or introduction in a place or condition): received into the church. 6. to the state, condition, or form assumed or brought about: went into shock; lapsed into disrepair; translated into another language. 7. to the occupation, action, possession, circumstance, or acceptance of: went into banking; coerced into complying. 8. (used to indicate a continuing extent in time or space): lasted into the night; far into the distance. 9. (used to indicate the number to be divided by another number): 2 into 20 equals 10. 10. Informal.interested or absorbed in, esp. obsessively: She's into yoga and gardening. 11. Slang.in debt to: I'm into him for ten dollars.
—adj. Math.pertaining to a function or map from one set to another set, the range of which is a proper subset of the second set, as the function f, from the set of all integers into the set of all perfect squares where f(x) = x2 for every integer.