The clutch is the mechanical-transmission counterpart of a torque converter.
A torque converter connects an engine to an automatic transmission through circulating fluid, while a manual-transmission clutch connects the engine to the gearbox through friction. In both cases, the device can interrupt the connection so the vehicle can start smoothly or the transmission can change ratios.
A manual clutch usually contains a flywheel, friction disc, pressure plate, release bearing and diaphragm spring. With the pedal released, spring pressure clamps the disc to the flywheel and sends engine torque into the transmission input shaft. With the pedal pressed, the disc separates and the gearbox can be shifted without forcing the gears to remain engine-driven.
The comparison is functional rather than literal. A torque converter can multiply torque during launch because its fluid flow and stator alter the relationship between input and output speed. A conventional dry clutch does not multiply torque; it mainly engages, disengages and modulates mechanical power. The flywheel is part of the surrounding clutch system, but it is not the counterpart by itself.