Machinery .

a part, as a disk, wheel, or section of a shaft, having cut teeth of such form, size, and spacing that they mesh with teeth in another part to transmit or receive force and motion.

an assembly of such parts.

one of several possible arrangements of such parts in a mechanism, as an automobile transmission, for affording different relations of torque and speed between the driving and the driven machinery, or for permitting the driven machinery to run in either direction

first gear; reverse gear.

a mechanism or group of parts performing one function or serving one purpose in a complex machine

steering gear.

implements, tools, or apparatus, esp. as used for a particular occupation or activity; paraphernalia

fishing gear.

a harness, esp. of horses.

Nautical .

the lines, tackles, etc., of a particular sail or spar.

the personal tools, clothing, and other possessions of a sailor.

portable items of personal property, including clothing; possessions

The campers keep all their gear in footlockers.

wearing apparel; clothing

The fashion pages of the Sunday paper are featuring the latest fall gear.

armor or arms.

to provide with or connect by gearing.

to put in or into gear.

to provide with gear; supply; equip.

to prepare, adjust, or adapt to a particular situation, person, etc., in order to bring about satisfactory results

The producers geared their output to seasonal demands.

to fit exactly, as one part of gearing into another; come into or be in gear.

Slang . great; wonderful. ?

gear down,

Automotive . to shift the transmission of a vehicle to a lower gear

The truck driver geared down at the top of the hill.

to reduce in scope or intensity

With less income you'll have to gear down your spending habits.

gear up,

to make or get ready for a future event or situation

Insiders say the senator is gearing up to run for governor.

to get or put on equipment or clothing for a particular purpose

The hikers geared up for the long trek down the mountain.

to arouse or excite, as with enthusiasm or expectation

The employees were geared up for a hard battle with management over working hours.

in gear

Machinery . in the state in which gears are connected or meshed

The car is in gear.

in proper or active working order; functioning continuously without trouble

Every department in this company must be in gear at all times.

in or into high gear, in or into a state of utmost speed, activity

or efficiency

Military rearmament moved into high gear.

out of gear

Machinery . in the state in which gears are not connected or meshed

The engine is out of gear.

shift or switch gears, to change one's attitude, course of action, methods, etc., in an abrupt, dramatic

or unexpected manner

In the middle of the second act the play shifts gears from comedy to tragedy.

noun

accessory , accouterment , adjunct , apparatus , appendage , appurtenance , baggage , belongings , contraption , effects , encumbrances , fittings , habiliment , harness , impedimenta , instrument , kit , kit and kaboodle , luggage , machinery , material , materiel , means , outfit , paraphernalia , possessions , rigging , setup , stuff , supply , tackle , things , tools , trappings , cog , cogwheel , gearwheel , pinion , ragwheel , sprocket , spurwheel , apparel , array , attire , clothes , costume , drapes , dress , duds * , feathers , garb , garments , habit , rags * , threads * , toggery , togs , wear , equipment , rig , thing , turnout , accouterments , appointments , draught-gear , gearing , mechanism

verb

accouter , adapt , adjust , appoint , arm , blend , fit , fit out * , furnish , harness , match , organize , outfit , ready , regulate , rig * , suit , tailor , turn out , equip , fit out , rig , accessory , apparatus , apparel , appliance , baggage , belongings , cam , clothing , cog , cogwheel , derailleur , dress , duds , equipment , garb , garments , goods , instrument , luggage , machine , materiel , mechanism , paraphernalia , personal effects , pinion , possessions , prepare , property , reverse , rigging , sprocket , stuff , supplies , tackle , things , trappings