http://dictionary.reference.com/search?q=font
 
A complete assortment of printing type of one size, including a due proportion of all the letters in the alphabet, large and small, points, accents, and whatever else is necessary for printing with that variety of types
 
A set of 
glyphs (
images) representing the
characters from some particular 
character set in a
particular size and 
typeface. The image of each character
may be encoded either as a 
bitmap (in a 
bitmap font) or by
a higher-level description in terms of lines and areas (an
outline font).
 
There are several different computer representations for
fonts, the most widely known are 
Adobe Systems, Inc.'s
PostScript font definitions and 
Apple's 
TrueType.
Window systems can display different fonts on the screen and
print them.