English
step stool
From step + stool.
Proto-Indo-European *stebʰ- ‘to support’
Proto-Germanic *stapjaną ‘to step’
Proto-West Germanic *stappjan ‘to step’
Old English steppan ‘to step’
Middle English steppen ‘to step’
English step
Proto-Indo-European *steh₂- ‘to stand’
…
Proto-Germanic *stōlaz ‘chair’
Proto-West Germanic *stōl ‘stool, chair’
Old English stōl ‘chair, seat’
Middle English stool
English stool
Today it means
noun A stool of various designs with one or more steps; in some designs the steps may be folded away underneath the seat when not in use.
Language periods are conventional ranges, not dates for this word.
Etymograph / step stool