Old English ta "toe" (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"). Perhaps originally meaning "fingers" as well (many PIE languages still use one word to mean both fingers and toes), and thus from PIE root *deik- "to show."

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

The old plural survived regionally into Middle English as tan, ton. To be on (one's) toes "alert, eager" is recorded from 1921. To step on (someone's) toes in the figurative sense "give offense" is from late 14c. Toe-hold "support for the toe of a boot in climbing" is from 1880.

large sea-fish of the mackerel order, 1520s, probably from French thon (14c.), from Old Provençal ton and directly from Latin thunnus "a tuna, tunny," from Greek thynnos "a tuna, tunny," possibly with a literal sense of "darter," from thynein "dart along."

 In ancient Greece, the food-fish par excellence, with its own vocabulary of culinary and market terms for the cuts and preparations of it.

1570s, "holy place of the Jewish tabernacle," from Latin sanctum "a holy place," as in Late Latin sanctum sanctorum "holy of holies" (translating Greek to hagion ton hagiou, translating Hebrew qodesh haqqodashim), from neuter of sanctus "holy" (see saint (n.)). In English, sanctum sanctorum attested from c. 1400; in the sense of "a person's private room or retreat" it is attested by 1706.

I had no need to make any change ; I should not be called upon to quit my sanctum of the school-room — for a sanctum it was now become to me —a very pleasant refuge in time of trouble. ["Jane Eyre"]