Plain English Meaning
The altitude number you actually see on the altimeter face after you've dialed in the correct local pressure setting. It is what the instrument is telling you right now.
Full Definition
The altitude read directly from a sensitive altimeter when its barometric scale (Kollsman window) is set to the current local altimeter setting. It represents the aircraft's height above mean sea level as displayed, uncorrected for nonstandard temperature.
Context Anchor
Seen when reading the altimeter in flight, setting the altimeter before takeoff, and comparing your displayed altitude with assigned or .