One of the cyclically repeating appearances of the moon or other orbiting body as seen from earth.

Portion of a physical system (liquid, gas, solid) that is homogeneous throughout, has definable boundaries, and can be separated physically from other phases.

An additive constant in the argument of a trigonometric function.

A constituent of an alloy that is physically distinct and is homogeneous in chemical composition.

1. The fractional part of a period through which the time variable of a periodic quantity (alternating electric current, vibration) has moved, as measured at any point in time from an arbitrary time origin; usually expressed in terms of angular measure, with one period being equal to 360° or 2π radians.

2. For a sinusoidally varying quantity, the phase (first definition) with the time origin located at the last point at which the quantity passed through a zero position from a negative to a positive direction.

3. The argument of the trigonometric function describing the space and time variation of a sinusoidal disturbance, y = A cos [(2π/λ)(x - vt )], where x and t are the space and time coordinates, v is the velocity of propagation, and λ is the wavelength.

The type of state of a system, such as solid, liquid, or gas.