toe (n.)

Middle English to (plural toon, sometimes toos), from Old English ta "digit of the human foot" (plural tan), contraction of *tahe (Mercian tahæ), from Proto-Germanic *taihwō(n) (source also of Old Norse ta, Old Frisian tane, Middle Dutch te, Dutch teen (perhaps originally a plural), Old High German zecha, German Zehe "toe").

Not considered related to Latin digitus, Greek daktylos, In historical Germanic languages apparently applied to the digits of the foot exclusively, but perhaps prehistorically meaning "fingers" as well (many PIE languages still use one word to mean both fingers and toes), and thus [Watkins] from PIE root *deik- "to show."

Þo stode hii I-armed fram heued to þe ton. [Robert of Gloucester, "Chronicle," c. 1300]

As "end of a stocking, shoe, boot, etc. which covers or contains the toes," from mid-15c. The old plural survived regionally and poetically as tan, ton. Toe-ring is attested by 1896.

To be on (one's) toes "alert, eager" is recorded from 1921. To turn up the toes "die" is from early 15c. . To step on (someone's) toes in the figurative sense "give offense" is from late 14c.; also in a similar sense was tread on (one's) heels (late 14c.). Toe-hold "support for the toe of a boot in climbing" is from 1880.

"touch or reach with the toes," 1813, from toe (n.). First in expression toe the mark, which seems to be nautical (variant toe the line is by 1826).

The chief mate ... marked a line on the deck, brought the two boys up to it, making them "toe the mark." [Richard H. Dana, "Two Years Before the Mast," 1840]

Related: Toed; toeing.