Proto-Indo-European root meaning "be sharp, rise (out) to a point, pierce."
It forms all or part of: acacia; acanthus; accipiter; acer; acerbic; acerbity; acervate; acervulus; acescent; acetic; acid; acicular; acme; acne; acrid; acridity; acrimony; acro-; acrobat; acromegaly; acronym; acrophobia; acropolis; acrostic; acrylic; acuity; aculeate; acumen; acupressure; acupuncture; acute; aglet; ague; Akron; anoxic; awn; coelacanth; dioxin; deoxy-; eager; ear (n.2) "grain part of corn;" edge (n.); egg (v.) "to goad on, incite;" eglantine; epoxy; ester; exacerbation; hammer; hypoxia; mediocre; oxalic; oxide; oxy-; oxygen; oxymoron; paragon; pyracanth; paroxysm; selvage; vinegar.
It is the hypothetical source of/evidence for its existence is provided by: Greek akros "at the end, at the top, outermost; consummate, excellent," akis "sharp point," akē "point of an iron tool," akantha "thorn," akmē "summit, edge," oxys "sharp, bitter;" Sanskrit acri- "corner, edge," acani- "point of an arrow," asrih "edge;" Oscan akrid (ablative singular) "sharply;" Latin acer (fem. acris) "sharp to the senses, pungent, bitter, eager, fierce," acutus "sharp, pointed," acuere "to sharpen," acerbus "harsh, bitter," acere "be sharp, be bitter," acus "a needle, pin," ocris "jagged mountain;" Lithuanian ašmuo "sharpness," akstis "sharp stick;" Old Lithuanian aštras, Lithuanian aštrus "sharp;" Old Church Slavonic ostru, Russian óstryj "sharp;" Old Irish er "high;" Welsh ochr "edge, corner, border;" Old Norse eggja "goad;" Old English ecg "sword;" German Eck "corner."
also *ker-, Proto-Indo-European root meaning "to cut."
It forms all or part of: bias; carnage; carnal; carnation; carnival; carnivorous; carrion; cenacle; charcuterie; charnel; corium; cortex; crone; cuirass; currier; curt; decorticate; excoriate; incarnadine; incarnate; incarnation; kirtle; scabbard; scar (n.2) "bare and broken rocky face of a cliff or mountain;" scaramouche; scarf (n.2) "connecting joint;" scarp; score; scrabble; scrap (n.1) "small piece;" scrape; screen; screw; scrimmage; scrofula; scrub (n.1) "low, stunted tree;" scurf; shard; share (n.1) "portion;" share (n.2) "iron blade of a plow;" sharp; shear; shears; sheer (adj.) "absolute, utter;" shirt; shore (n.) "land bordering a large body of water;" short; shrub; skerry; skirmish; skirt.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit krnati "hurts, wounds, kills," krntati "cuts;" Hittite karsh- "to cut off;" Greek keirein "to cut, shear;" Latin curtus "short," caro (genitive carnis) "flesh" (originally "piece of flesh"); Lithuanian skiriu, skirti "to separate;" Old English sceran, scieran "to cleave, hew, cut with a sharp instrument;" Old Irish scaraim "I separate;" Welsh ysgar "to separate," ysgyr "fragment."
c. 1500, "a sharp, piercing sound or cry," expressive of pain, alarm, etc., from scream (v.).
And (as they say) lamentings heard i' th' Ayre; Strange Schreemes of Death. ["Macbeth," II.iii.61]
That spelling probably reflects "sk-" as spelled in words from Latin (such as school; see sch); his early editions also have schreene for screen. The slang meaning "something very great, excellent, or exciting," especially "something that evokes a cry of laughter" is by 1888; screamer in this sense is from 1831.
It forms all or part of: derm; -derm; derma; dermal; dermato-; dermatology; echinoderm; epidermis; hypodermic; pachyderm; scleroderma; taxidermy; tart (adj.) "having a sharp taste;" tear (v.1) "pull apart;" tetter; turd.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit drnati "cleaves, bursts;" Greek derein "to flay;" Armenian terem "I flay;" Old Church Slavonic dera "to burst asunder;" Breton darn "piece;" Old English teran "to tear, lacerate."
also *peik-, Proto-Indo-European root meaning "to cut, mark by incision," hence "embroider, paint."
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit pimsati "to carve, hew out, cut to measure, adorn;" Greek pikros "bitter, sharp, pointed, piercing, painful," poikilos "spotted, pied, various;" Latin pingere "to embroider, tattoo, paint, picture;" Old Church Slavonic pila "file, saw," pegu "variegated," pisati "to write;" Lithuanian piela "file," piešiu, piešti "to write;" Old High German fehjan "to adorn."