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Escalate, as in "tensions escalate," comes from the word escalator, which originated as a trademarked term for the Otis Elevator Company's moving staircase.
The public first encountered the word escalator – but with a capital, Escalator – when the technology was demonstrated at the Paris Exposition in 1900.
Oddly, although mechanical escalators go up and down, the verb escalate – which first appeared in print in 1944 – refers only to things rising (both literally and figuratively).
Because Otis did little to protect its rights to the mark, a 1950 court ruling moved escalator into the public domain.