Glossary Term Definition
The parts of letterforms that extend above the x-height (ascenders) or below the baseline (descenders), as in b, d, f, g, h, j, k, l, p, q, and y.
Definition
The parts of letterforms that extend above the x-height (ascenders) or below the baseline (descenders). Letters with extenders include b, d, f, g, h, j, k, l, p, q, and y. The length and treatment of extenders are significant factors in a typeface's texture and readability.
Source
No access — Robert Bringhurst — p. 324:
The parts of letterforms that extend above the x-height or below the baseline.