Q - Quality factor of an inductor or capacitor. It is the ratio of a component's reactance (energy stored) to its effective series resistance (energy dissipated). For a tuned circuit, a figure of merit used in bandwidth calculations. Q is the ratio of reactive power to resistive power in a tuned circuit. Also the symbol for charge in coulombs (Q for quantity).
quiescent - At rest. For an amplifier the term is used to describe a condition with no active input signal.
quiescent point - (Q point) A point on the DC load line of a given amplifier that represents the quiescent (no signal) value of output voltage and current for the circuit.