BT BB 4a(26) :אפיק סאפא ועייל סאפא כי היכי דליקביל סידא‏ : he made a row (of stones) stick out and a row go in so that (the wall) would accept the plaster
See the entire entry for npq vb. to go out

BT BB 4a(26) :אפיק סאפא ועייל סאפא כי היכי דליקביל סידא‏ : he made one course protrude and one row recede so that the plaster would be accepted
See the entire entry for sḥāp̄, sḥāp̄ā v.n. laying down, throwing down

BT BB 4a(26) :כי היכי דליקביל סידא‏ : so that (the wall) would grasp the plaster
See the entire entry for sēḏ, saydā n.m. lime, plaster