self-acting

[ self-ak-ting ]

/ ˈsɛlfˈæk tɪŋ /

acting by itself; automatic.

Origin of self-acting

First recorded in 1670–80

self-ac·tion, noun

When the scars or grooves in which a habit runs are made deep, the habit becomes automatic or self-acting and perhaps involuntary.

Alcohol and the Human Brain |Joseph Cook
Not if he is a wise man, and has a patent Nelson self-acting parachute fastened to him all the time!

The Boy Scouts at the Panama-Pacific Exposition |Howard Payson
A gentle pressure on the trigger revealed the pleasing fact that the revolver was of a self-acting type.

A Lively Bit of the Front |Percy F. Westerman
We have considered, on a former page, that we are not to look for the self-acting individuals among the workingmen as a class.

The Holy Earth |L. H. Bailey

The engine is self-acting, and can be driven either by hand or by a steam-engine or other motive power.

Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 3 |Various

self-acting

not requiring an external influence or control to function; automatic

self-action, noun