BT Šab 34a(43) :ספיקא דרבנן הוא‏ : it is a doubt of a rabbinic injunction
See the entire entry for sp̄eq, sp̄ēqā n.m. doubt

BT Šab 34a(43) :וספיקא דרבנן לקולא‏ : a doubt (according to the) rabbis' interpretation is resolved in the lenient fashion
See the entire entry for qol, qullā n.m. lenient decision