Midheaven
The zodiac degree crossing the local meridian at birth, the high point of the ecliptic in that sky. Abbreviated MC. The most public angle of the chart: work in the world, reputation, direction.
Halfway through its daily arc, every degree of the zodiac crosses the meridian, the north to south line that divides the sky overhead. The degree doing so at the moment of birth is the Midheaven, from the Latin medium coeli, middle of the sky, written MC.
It is the most visible point of the chart, and astrologers read it accordingly: vocation, public standing, the direction a life points when it points outward. Its opposite, the IC or imum coeli, marks the sky's low point and the private root of the chart, home and origin.
In quadrant house systems such as Placidus, the Midheaven is also the cusp of the tenth house. In whole sign houses it floats, often landing in the ninth, tenth, or eleventh, which is one of the visible differences between the systems.