Etymology
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relax (v.)

late 14c., relaxen, "to make (something) less compact or dense" (transitive), originally especially in medicine, of muscles, etc., from Old French relaschier "set free; soften; reduce" (14c.) and directly from Latin relaxare "relax, loosen, open, stretch out, widen again; make loose," from re- "back" (see re-) + laxare "loosen," from laxus "loose" (from PIE root *sleg- "be slack, be languid"). A doublet of release.

Meaning "decrease tension" is from early 15c. From 1660s as "to make less severe or rigorous." Intransitive sense of "become loose or languid" is by 1762; that of "become less tense" is recorded from 1935. Of persons, "to become less formal," by 1837. Related: Relaxed; relaxing. As a noun, "relaxation, an act of relaxing," from 17c.

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relaxant (adj.)

1771, "causing or distinguished by relaxation," from Latin relaxantem (nominative relaxans), present participle of relaxare "to loosen, stretch out" (see relax). As a noun, "a medicine or treatment that relaxes or opens," from 1832. An earlier adjective was relaxative "having the quality of relaxing" (1610s).

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pyrolusite (n.)

"manganese dioxide," a common ore, 1828, from Greek elements pyro- "by heat, by fire" (from PIE root *paewr- "fire") + lysis "a loosening" (from PIE root *leu- "to loosen, divide, cut apart"). The name was given in Roman times, when the substance was used, in a heated state, to de-colorize glass.

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lease (v.)

late 15c., "to take a lease," from Anglo-French lesser (13c.), Old French laissier "to let, let go, let out, leave" "to let, allow, permit; bequeath, leave," from Latin laxare "loosen, open, make wide," from laxus "loose" (from PIE root *sleg- "be slack, be languid"). Medial -x- in Latin tends to become -ss- or -s- in French (compare cuisse from coxa). The Latin verb also is the source of Spanish laxar; Italian lasciare "leave," lassare "loosen."

Compare release (v.). Meaning "to grant the temporary possession of at a fixed rate" is from 1560s. Related: Leased; leasing. The form has been influenced by the noun, and the modern sense of "to take a lease" might be a new 19c. formation. Lessor, lessee in contract language preserve the Anglo-French vowel.

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Gordian knot (n.)

1560s, tied by Gordius (Greek Gordios), first king of Phrygia in Asia Minor and father of Midas, who predicted the one to loosen it would rule Asia. Instead, Alexander the Great cut the Gordian knot with his sword; hence the extended sense (1570s in English) "solve a difficult problem in a quick, dramatic way."

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laxative (adj.)

late 14c., "causing relaxation or looseness," from Old French laxatif (13c.), from Medieval Latin laxativus "loosening," from Latin laxat-, past participle stem of laxare "loosen," from laxus "loose, lax" (see lax). The noun meaning "a laxative medicine, a medicine that relieves constipation by relaxing the intestines" is from late 14c.

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resolve (v.)

late 14c., resolven, "melt, dissolve, reduce to liquid; separate into component parts; alter, alter in form or nature by application of physical process," " intransitive sense from c. 1400; from Old French resolver or directly from Latin resolvere "to loosen, loose, unyoke, undo; explain; relax; set free; make void, dispel."

This is from re-, here perhaps intensive or meaning "back" (see re-), + solvere "to loosen, untie, release, explain," from PIE *se-lu-, from reflexive pronoun *s(w)e- (see idiom) + root *leu- "to loosen, divide, cut apart."

From the notion of "separate into components" comes the sense in optics (1785; see resolution). From the notion of "reduce by mental analysis into its basic forms" (late 14c.) comes the meaning "determine, decide upon" after analysis (1520s), hence "pass a resolution" (1580s); "decide, settle" a dispute, etc. (1610s). For sense evolution, compare resolute (adj.).

In Middle English also "vaporize a solid, condense a vapor into a liquid, etc.;" a mid-15c. document has Sche was resoluyd in-to terys where a later writer might have she dissolved in tears. Related: Resolved; resolving.

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dialysis (n.)

1580s, in logic and grammar, in the latter "division of one syllable into two," from Latin, from Greek dialysis "dissolution, separation" (used of the disbanding of troops, a divorce, etc.), from dialyein "dissolve, separate," from dia "apart" + lyein "loosen" (from PIE root *leu- "to loosen, divide, cut apart").

Chemistry sense of "process by which particles are selectively removed from a liquid by consequence of their differing capacity to pass through a membrane into another liquid" is from 1861; the specific sense in medicine, "process of blood purification by allowing it to pass through a membrane" is by 1914. Related: Dialytic. The verb dialyze was formed from the noun on the model of analyze, etc.

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*leu- 

Proto-Indo-European root meaning "to loosen, divide, cut apart."

It forms all or part of: absolute; absolution; absolve; analysis; analytic; catalysis; catalyst; catalytic; dialysis; dissolve; electrolysis; electrolyte; forlorn; Hippolytus; hydrolysis; -less; loess; loose; lorn; lose; loss; Lysander; lysergic; lysis; -lysis; lyso-; lysol; lytic; -lytic; palsy; paralysis; pyrolusite; resolute; resolution; resolve; soluble; solute; solution; solve; solvent.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit lunati "cuts, cuts off," lavitram "sickle;" Greek lyein "to loosen, untie, slacken," lysus "a loosening;" Latin luere "to loose, release, atone for, expiate;" Old Norse lauss "loose, free, unencumbered; vacant; dissolute;" Old English losian "be lost, perish."

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analytics (n.)

"the division of logic which distinguishes good from bad arguments," 1590s, from Latin analytica from Greek analytika, from stem of analyein "unloose, release, set free," from ana "up, back, throughout" (see ana-) + lysis "a loosening," from lyein "to unfasten" (from PIE root *leu- "to loosen, divide, cut apart"); also see -ics. Ta Analytika was the name of Aristotle's treatises on logic.

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