Also see definition of "Proper" in Word Study
Proper
PROPER [isbe]
PROPER - prop'-er: For the King James Version "proper" (child), in Heb 11:23, the Revised Version (British and American) substitutes "goodly"; in 1 Ch 29:3; 1 Cor 7:7, the Revised Version (British and American) "own" is employed, and for the too emphatic "their proper tongue" in Acts 1:19 "their language" is written. But none of the King James Version forms are really obsolete.
Also see definition of "Proper" in Word Study