Partial Metering
A metering pattern reading roughly the central eight to fifteen per cent of the frame — broader than spot, narrower than centre-weighted.
In depth
Partial metering is a Canon speciality that fills the gap where a spot is too easy to misplace but a centre-weighted average is too diluted by a bright or dark surround. It is especially useful for head-and-shoulders portraits in backlight, where the face fills roughly that proportion of the frame.
Examples in practice
A backlit portrait metered partial off the face needs perhaps +⅓ EV, where matrix metering would need +1⅔ EV.