1844, "to act as an optimist, take the most hopeful view of a matter," a back-formation from optimist. Meaning "to make the most of, develop to the utmost" is attested by 1857. Related: Optimized; optimizing.
mid-13c., muk, "animal or human excrement; cow dung and vegetable matter spread as manure," from a Scandinavian source such as Old Norse myki, mykr "cow dung," Danish møg; from Proto-Germanic *muk-, *meuk- "soft," which is perhaps related to Old English meox "dung, filth" (see mash (n.)). Meaning "unclean matter generally" is from c. 1300; that of "wet, slimy mess" is by 1766. Muck-sweat "profuse sweat" is attested from 1690s.
c. 1400, from Old French loialte, leaute "loyalty, fidelity; legitimacy; honesty; good quality" (Modern French loyauté), from loial (see loyal). The Medieval Latin word was legalitas. The earlier Middle English form was leaute (mid-13c.), from the older French form. Loyalty oath first attested 1852.
Allegiance ... is a matter of principle, and applies especially to conduct; the oath of allegiance covers conduct only. Loyalty is a matter of both principle and sentiment, conduct and feeling; it implies enthusiasm and devotion .... [Century Dictionary, 1897]
c. 1400, coagulacioun, "act of changing from a fluid to a thickened state," from Latin coagulationem (nominative coagulatio), noun of action from past participle stem of coagulare "cause to curdle" (see coagulate). Meaning "mass or quantity of coagulated matter" is from 1660s.