acne n.

"highest point," 1560s, from Greek akmē "(highest) point, edge; peak of anything," hence "prime (of life, etc.), the best time" (from PIE *ak-ma-, suffixed form of root *ak- "be sharp, rise (out) to a point, pierce"). In English it was written in Greek letters until c. 1620. The U.S. grocery store chain was founded 1891 in Philadelphia, Pennsylvania.

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."