S: (n) reducer (pipefitting that joins two pipes of different diameter)
S: (n) receptacle (an electrical (or electronic) fitting that is connected to a source of power and equipped to receive an insert)
S: (n) outlet box ((electricity) receptacle consisting of the metal box designed for connections to a wiring system)
S: (n) slot, expansion slot ((computer) a socket in a microcomputer that will accept a plug-in circuit board) "the PC had three slots for additional memory"
S: (n) socket (a receptacle into which an electric device can be inserted)