early 14c., "alphabetic element other than a vowel," from Latin consonantem (nominative consonans) "sounding together, agreeing," as a noun, "a consonant" (consonantem littera), present participle of consonare "to sound together, sound aloud," from assimilated form of com "with, together" (see con-) + sonare "to sound, make a noise" (from PIE root *swen- "to sound").

Consonants were thought of as sounds that are produced only together with vowels. Related: Consonantal.

early 15c., "agreeing, corresponding, harmonious," from Old French consonant (13c.) and directly from Latin consonantem (nominative consonans) "sounding together, agreeing," present participle of consonare "to sound together, sound aloud," from assimilated form of com "with, together" (see con-) + sonare "to sound, make a noise" (from PIE root *swen- "to sound").

Of music, c. 1600; of words, 1640s. Related: Consonantly.

late 14c., "pleasing combination of sounds, harmony," from Old French consonance (12c.) "consonance, rhyme" and directly from Latin consonantia "harmony, agreement," from consonantem (nominative consonans) "agreeing in sound," present participle of consonare "to sound together, sound aloud" (see consonant (adj.)).

From early 15c. as "agreement among persons as to facts or opinions." Meaning "accord or agreement of sounds in words or syllables" is from 1580s.

also swenə-, Proto-Indo-European root meaning "to sound." 

It forms all or part of: assonance; consonant; dissonant; resound; sonant; sonata; sone; sonic; sonnet; sonogram; sonorous; sound (n.1) "noise, what is heard;" sound (v.1) "to be audible;" swan; unison.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit svanati "it sounds," svanah "sound, tone;" Latin sonus "sound, a noise," sonare "to sound;" Old Irish senim "the playing of an instrument;" Old English geswin "music, song," swinsian "to sing;" Old Norse svanr, Old English swan "swan," properly "the sounding bird."

one of the three districts, anciently under the government of a a reeve,  into which Yorkshire was divided, late 13c., from late Old English *þriðing, a relic of Viking rule, from Old Norse ðriðjungr "third part," from ðriði "third" (see third).

The initial consonant apparently was merged by misdivision with final consonant of preceding north, west, or east.

"to form hypotheses," 1738, from hypothesis + -ize. Hypothetize is an alternative form, preserving the consonant of the Greek base. Related: Hypothesized; hypothesizing.