ARM/LEG: An upper or lower (horizontal or diagonal) stroke that is attached on one end and free on the other.
ASCENDER: The part of a lowercase character (b, d, f, h, k, l, t) that extends above the x-height.
BAR: The horizontal stroke in characters such as A, H, R, e, and f.
BOWL: A curved stroke which creates an enclosed space within a character (the space is then called a counter).
CAP HEIGHT: The height of capital letters from the baseline to the top of caps, most accurately measured on a character with a flat bottom (E, H, I, etc.).
COUNTER: The partially or fully enclosed space within a character.
DESCENDER: The part of a character (g, j, p, q, y, and sometimes J) that descends below the baseline.
EAR: The small stroke that projects from the top of the lowercase g.
LINK: The stroke that connects the top and bottom part (bowl and loop) of a two-story lowercase g.
LOOP: The lower portion of the lowercase g.
SERIF: The projections extending off the main strokes of the characters of serif typefaces. Serifs come in two styles: bracketed and unbracketed. Brackets are the supportive curves which connect the serif to the stroke. Unbracketed serifs are attached sharply, and usually at 90 degree angles.
SHOULDER: The curved stroke of the h, m, n.
SPINE: The main curved stroke of the S.
SPUR: A small projection off a main stroke found on many capital Gs.
STEM: A straight vertical stroke (or the main straight diagonal stroke in a letter which has no verticals).
STRESS: The direction of thickening in a curved stroke.
STROKE: A straight or curved line.
SWASH: A fancy flourish replacing a terminal or serif.
TAIL: The descender of a Q or short diagonal stroke of an R.
TERMINAL: The end of a stroke not terminated with a serif.
X-HEIGHT: The height of lowercase letters, specifically the lowercase x, not including ascenders and descenders.