self-acting
A2Ածական/US /sɛlf-ˈæktɪŋ/ sĕlf-ĂKT-ĭng; UK /sɛlf-ˈæktɪŋ/ sĕlf-ĂKT-ĭng/
Acting of or by one's self or by itself; -- said especially of a machine or mechanism which is made to perform of or for itself what is usually done by human agency; automatic; as, a self-acting feed apparatus; a self-acting mule; a self-acting press.
