plural of second gear

An angle, one sixtieth (1/60th) of a minute of arc or one 3600th of a degree.

The second gearing available from a gearbox. / (idiomatic, figuratively) Mediocre, sluggish performance.

Alternative spelling of second-class

The second-lowest rank in the Boy Scouts of America, between tenderfoot and first class.

(neutral or mildly positive connotation) Of a standard or grade one level below the best. / (negative connotation) Inferior in quality or standing.

A person who plays second string. A person who is kept on a sports team as a backup in case a "first-string" player is unavailable.

(UK) Alternative form of on second thought

As good as the best, as in quality or reputation; inferior to no one else or to nothing else of the same kind.

(slang, sometimes capitalized) Heroin.