[1] : WordNet (r) 2.0

turn in
     v 1: make an entrance by turning from a road; "turn in after you
          see the gate"
     2: to surrender someone or something to another; "the guard
        delivered the criminal to the police"; "render up the
        prisoners"; "render the town to the enemy"; "fork over the
        money" syn: hand over, fork over, fork out, fork
        up, get in, deliver, render
     3: carry out performances; "they turned in a splendid
        effort"; "they turned in top jobs for the second straight
        game" syn: put on
     4: go to bed in order to sleep; "i usually turn in at
        midnight"; "he turns out at the crack of dawn" syn: go
        to bed, bed, crawl in, kip down, hit the hay, hit
        the sack, sack out, go to sleep, retire ant: get
        up, get up
see also:
hand over fork over fork out fork up get in deliver 
render put on go to bed bed crawl in 
kip down hit the hay hit the sack sack out go to sleep 
retire get up get up 

[2] : Moby Thesaurus II by Grady Ward, 1.0

40 moby thesaurus words for "turn in":
   bed, betray, convert, crash, crawl in, doss down, double-cross,
   evert, flop, hit the hay, hit the sack, inform on, introvert,
   intussuscept, invaginate, inverse, invert, kip down, let down,
   pronate, resupinate, reverse, revolve, roll in, rotate, sack out,
   sack up, sell out, supinate, transpose, turn about, turn around,
   turn down, turn inside out, turn out, turn over, turn the scale,
   turn the tables, turn upside down, two-time

Round Turn >> R Words
Round Turn, definition of term: Round Turn
round+turn_pag1.html

In Turn >> I Words
In Turn, definition of term: In Turn
in+turn_pag1.html