acro- Look up acro- at
word-forming element meaning "highest, topmost, at the extremities," before vowels, acr-, from Latinized form of Greek akro- "pertaining to an end, extreme," from akros "at the end, at the top, outermost; consummate, excellent" from PIE *akri-, from the root *ak- "be sharp, rise (out) to a point, pierce" (source also of Oscan akrid (ablative singular) "sharply;" Greek akis "sharp point," akros "at the farthest point, highest, outermost," akantha "thorn," akme "summit, edge," also oxys "sharp, bitter;" Sanskrit acri- "corner, edge," acani- "point of an arrow," asrih "edge;" 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").