French word lorsque comes from French que, French lors ((obsolete) then, at that time.)

Detailed word origin of lorsque

Dictionary entry	Language	Definition
que	French (fra)	(used with ne) only (ne ... que parses roughly as "(do[es]) not / nothing ... other than"). Links two noun phrases in apposition forming a clause without a (finite) verb, such that the complement acts as predicate.. Substitutes for another, previously stated conjunction.. That (introduces a noun clause and connects it to its parent clause). When, no sooner. Than (introduces a comparison) [...]
lors	French (fra)	(obsolete) then, at that time.
lorsque	French (fra)	When (at a time when).