self-acting

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

Not if he is a wise man, and has a patent Nelson self-acting parachute fastened to him all the time!

A gentle pressure on the trigger revealed the pleasing fact that the revolver was of a self-acting type.

We have considered, on a former page, that we are not to look for the self-acting individuals among the workingmen as a class.