APARTMENT - this sign is what is known as a fingerspelled loan sign.
Fingerspelled loan signs are commonly used fingerspellings that are
two-to-five letters in length and that have their own unique patterns
of movement. The fingerspellings and their unique patterns of movement
have become lexical items in ASL.
DORM - is another initialized sign; notice the D-handshape. We've seen
a few at this point. It is based on the sign HOME. [Note that the
similar sign DEAF is never initialized; the sign DEAF has an extended
index finger, not a D-handshape.]
HOME is historically derived from a compound of the signs EAT and
SLEEP. Notice how the pictorial qualites of the signs EAT and SLEEP
are lost in the sign HOME.