Quote Originally Posted by bublinka View Post
Из них построено живое,
Живое в ней же и сидит,
В нее простой тетрадный лист.
Живете вы с соседом двое
На ней одной. И есть одна
В груди у вас. И кто она?
I figured out this one based on the first three lines, although I had never heard the word in the sense described by "есть одна в груди у вас" -- but I found it by going to the "disambiguation" (другие значения) link in Wikipedia! Anyway, it's:

"клетка"
Which in English can be variously translated as:
"cell" in the biological sense
"grid-square, as on graph paper or on a chessboard"
"a cage"
"a landing in a stairwell"
"chest cavity", i.e., the interior of the ribcage