room, hole, unit, ring
Cell
cell, crop
CELL, as in cell phone, I guess.
Cyto
Wall
The word heart is another four-letter word that is related to your circulatory system.
Cage is a four-letter word that starts with c and means cell. Or case! Or the 5 letter word Crypt!
door?
'Cans' is another word for 'tins'.
over
sawn
halt