Lewis & Short

căcūmen, ĭnis, n. [etym. dub.], the extreme end, extremity, or point of a thing; the peak, top, utmost point.

  1. I. Lit. (whether horizontal or perpendicular; while culmen is an extremity projecting in height; v. Doed. Syn.; in the poets freq.; in prose rare before the Aug. per.; not in Cic.): ut altis Arboribus vicina cacumina summa terantur Inter se, the extreme top, Lucr. 1, 898.
    So of tree-tops: umbrosa cacumina, Verg. E. 2, 3: fracta, id. ib. 9, 9; 6, 28; id. G. 2, 29; 2, 307; Ov. M. 1, 346; 1, 552; 1, 567; 8, 257; 8, 716; 8, 756; 9, 389; 10, 140; 10, 193; 13, 833; 15, 396; Quint. 8, 3, 10; 1, 2, 26: arborum cacumina, Plin. 10, 53, 74, § 147: ficorum, pirorum, malorum, Col. 3, 21, 11: olivae, id. 5, 11, 14 and 15; 11, 3, 37; Pall. Jan. 15, 15; id. Febr. 25, 28; id. Mart. 10, 23; 10, 35; id. Apr. 4, 1; Veg. 4, 4, 9 al.: harundinis, Plin. 16, 36, 64, § 158.
    Of grass, the points of the blades, Ov. Tr. 3, 12, 12: praeacutis (ramorum) cacuminibus, Caes. B. G. 7, 73; Lucr. 6, 459.
    Of the summits, peaks of mountains, Liv. 7, 34, 4; Lucr. 6, 464; Cat. 64, 240; Verg. A. 3, 274; Hor. Epod. 16, 28; Ov. M. 1, 310; 1, 317; 1, 666; 6, 311; 8, 797; 7, 804; 9, 93; Luc. 7, 75, Plin. 3, 16, 20, § 117; 6, 7, 7, § 20 al.
    Of other things: pilorum, Auct. B. Afr. 47: atomi, Lucr. 1, 600: cujusque rei, id. 1, 750: ovi, Plin. 10, 52, 74, § 145; 10. 54, 75, § 151: metae, id. 36, 5, 4, § 31: pyramidis, id. 36, 12, 17, § 79: membrorum, id. 11, 37. 88, § 219: ignis, Luc. 1, 551: incurvum, of the elephant’s back, Sil. 9, 584.
  2. II. Trop.
    1. A. The end, limit: donec alescundi summum tetigere cacumen, until they have completely attained the limit of their growth, Lucr. 2, 1130: ad summum donec venere cacumen, to the height of perfection, id. 5, 1456: famae, Laber. ap. Macr. S. 2, 7.
    2. B. As a gram. t. t., the mark of accent placed over a letter, Mart. Cap. 3, § 273.