Railroads. that part of a rail in contact with the treads of wheels.
—Idioms
21.
tread on someone's toes or corns, to offend or irritate someone.
22.
tread the boards, to act on the stage, esp. professionally: He recalled the days when he had trod the boards.
23.
tread water,
a.
Swimming. to maintain the body erect in the water with the head above the surface usually by a pumping up-and-down movement of the legs and sometimes the arms.
b.
Slang. to make efforts that maintain but do not further one's status, progress, or performance: He's just treading water here until he can find another job.
Origin: bef. 900; (v.) ME treden, OE tredan; c. OFris treda, OS tredan, D treden, G treten; akin to ON trotha, Goth trudan; (n.) ME tred footprint, deriv. of the v.