portamento

A smooth uninterrupted glide in passing from one tone to another, especially with the voice or a bowed stringed instrument.

In music for the voice or an instrument of the viol family, a gradual change or gliding from one pitch or tone to another without break or perceptible step.

In singing, or in the use of the bow, a gradual carrying or lifting of the voice or sound very smoothly from one note to another; a gliding from tone to tone.

A smooth, gliding transition from one note to another; used especially with stringed instruments, and sometimes on brass.