A number of analogue synthesisers designed by Dr. Robert Moog or manufactured by Moog Music, and commonly used as a generic term for analogue and digital music synthesizers during the 1970s.
The Minimoog (shown) was a monophonic analogue synth released in 1970 and was one of the first widely available, portable and relatively affordable (it was around $1500 on release) synthesizers at that time.