(originally in ancient Irish religion and mythology) A (generally magical) vow, obligation or injunction placed upon someone to do or not do something, which typically brings harm if violated and blessings if obeyed.

An enclosed gear train. / That part of a car's transmission containing the train of gears, and to which the gear lever is connected.

(uncountable) Equipment or paraphernalia, especially that used for an athletic endeavor. / Clothing; garments. / (obsolete) Goods; property; household items.

(engineering, transitive) To provide with gearing; to fit with gears in order to achieve a desired gear ratio. / (engineering, intransitive) To be in, or come into, gear.

(chiefly Liverpudlian) great or fantastic

The third gear of an engine.

The first gear of an transmission, which provides the lowest output speed and greatest mechanical advantage.

The fifth and typically highest gear of an engine.

(US, idiomatic) To exert effective effort; to get going; to get moving; to start producing.

An arrangement of bevel gears permitting the rotation of two shafts at two different speeds whilst supplying the same torque; used on the drive axles or between the driven wheels of automobiles to aid cornering.