room, apartment, chamber, greenhouse, cellar
室 centers on an enclosed space within a building: a room, chamber, or apartment. Specialized uses like greenhouse or cellar are natural extensions of a defined interior space.
室 combines 宀 (roof) with 至, which likely contributes the sound and the idea of arriving or settling, suggesting a place where one settles under a roof.
Under a roof 宀, the shape 至 looks like a person arriving and settling into a room. Picture a traveler reaching their chamber and closing the door.
For シツ, imagine a sheet hanging over the room: sheet -> シツ, and the roof 宀 is like a sheet covering the space.
room
classroom; lecture room
single (room); room for one; one's own room; private room; private compartment
indoor; inside the room
guest room (at a hotel); guest cabin (on a boat); passenger cabin (on a plane)
bedroom
Imperial household
royal family
locked room
bathroom
greenhouse; hothouse; conservatory; glasshouse
waiting room
one's own room
Muromachi period (1336-1573)
sickroom; hospital room; ward
section chief; laboratory manager; office head; room monitor
Japanese-style room
entering a room
one room
same room
separate room; another room
tearoom; tea house; tea-ceremony room; tea arbour; tea arbor
waiting room; anteroom; antechamber; green room
chamber music
stateroom; cabin
living room
Western-style room
next or adjoining room
stone hut; rock chamber
detached office; annex
office (room)
planning office
conference room; council room
library (usu. single-room); small library
cellar; basement
laboratory
locker room; changing room; dressing room
laboratory