step-ladder (n.)

Old English steppa (Mercian), stæpe, stepe (West Saxon) "stair, act of stepping," from the source of step (v.). Compare Old Frisian, Middle Dutch, Dutch stap, Old High German stapfo, German Stapfe "footstep").

It is attested from late Old English as "degree on a scale." The figurative meaning "action which leads toward a result" is recorded from 1540s. In dancing, from 1670s. The meaning "type of military pace" is from 1798.

The warning phrase watch your step is attested from 1911 (Wycliffe, late 14c., has keep thy foot in essentially the same sense). Step by step indicating steady progression is from 1580s. To follow in (someone's) steps is from mid-13c.

Old English hlæder "ladder, steps," from Proto-Germanic *hlaidri (source also of Old Frisian hledere, Middle Dutch ledere, Old High German leitara, German Leiter), from suffixed form of PIE root *klei- "to lean" (source also of Greek klimax "ladder"). In late Old English, rungs were læddrestæfæ and the side pieces were ledder steles. The belief that bad things happen to people who walk under ladders is attested from 1787, but its origin likely is more scientific than superstitious.