late Old English ofer-done "carried to excess, immoderate, too much;" see overdo. Of meat, etc., "cooked too much," from 1680s.

Old English blæcan, of cloth or fabric, "to make white by removing color, whiten" (by exposure to chemical agents or the sun), from Proto-Germanic *blaikjan "to make white" (source also of Old Saxon blek, Old Norse bleikr, Dutch bleek, Old High German bleih, German bleich "pale;" Old Norse bleikja, Dutch bleken, German bleichen "to make white, cause to fade"), from PIE root *bhel- (1) "to shine, flash, burn," also "shining white."

The same root probably produced black, perhaps because both black and white are colorless, or because both are associated in different ways with burning. Compare Old English scimian meaning both "to shine" and "to dim, grow dusky, grow dark," which is related to the source of shine. Intransitive sense "become white" is from 1610s. Related: Bleached; bleaching. The past participle in Middle English was sometimes blaught.

"person who seeks or is put forward for an office by election or appointment," c. 1600, from Latin candidatus "one aspiring to office," originally "white-robed," past participle of candidare "to make white or bright," from candidus past participle of candere "to shine," from PIE root *kand- "to shine." White was the usual color of the Roman toga, but office-seekers in ancient Rome wore a gleaming white toga (togacandida), probably whitened with fine powdered chalk, presumably to indicate the purity of their intentions in seeking a role in civic affairs.

"piece of wood," 1670s; "piece of meat," 1723; probably a variant of chock (n.) "block." "Chock and chuck appear to have been originally variants of the same word, which are now somewhat differentiated" [OED].

Chock and Chuck, Are low terms, very frequently used before full,—as the coach was chock full of passengers. The house was chuck full. [Daniel Powers, "A Grammar on an Entirely New System," West Brookfield, 1845]

Specifically of shoulder meat from early 18c. (the exact cut varies from place to place). Meaning "device for holding work in a lathe or other machine" is from 1703 (also chock). American English chuck wagon (1880) is from a mid-19c. meaning "food, grub," generalized from the meat sense.