Into

[in-too; unstressed in-too, -tuh] /ˈɪn tu; unstressed ˈɪn tʊ, -tə/

preposition
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, especially obsessively:
She’s into yoga and gardening.
11.
Slang. in debt to:
I’m into him for ten dollars.
adjective
12.
Mathematics. 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) = x 2 for every integer.
/ˈɪntuː; unstressed ˈɪntə/
preposition
1.
to the interior or inner parts of: to look into a case
2.
to the middle or midst of so as to be surrounded by: into the water, into the bushes
3.
against; up against: he drove into a wall
4.
used to indicate the result of a transformation or change: he changed into a monster
5.
(maths) used to indicate a dividend: three into six is two
6.
(informal) interested or enthusiastically involved in: I’m really into Freud these days
prep.

Old English into, originally in to. The word is a late Old English development to replace the fading dative case inflections that formerly distinguished, for instance, “in the house” from “into the house.” To be into something, “be intensely involved in,” first recorded 1969 in American English.

adverb phrase

Doing the sex act; making love: Like Kirkland’s book, Tharp’s even includes a discussion of what Baryshnikov is like in the sack (1960s+)