legal term, from Latin sistere "to cause to stand" (see assist).
Online Etymology Dictionary, © 2010 Douglas Harper
Examples from the Web for sist
Would not Miss Alice like a waitin'-maid sent to 'sist her in dressin'?Eventide
Sist' Humphreys be'n an edicated lady; an' she is a plumb good cook.Stories That End Well
Cist, sist, n. a tomb consisting of a stone chest covered with stone slabs.
Cyst, sist, n. a bag in animal bodies containing morbid matter.
Discur′sion, desultory talk: act of reasoning; Discur′sist, a disputer.