1. apex(n = noun.location) acme, peak, vertex - the highest point (of something); "at the peak of the pyramid"
is a kind of extreme, extreme point, extremum
has particulars: crown, roof peak
Derived form adjective apical1
2. apex(n = noun.location) apex of the sun's way, solar apex - the point on the celestial sphere toward which the sun and solar system appear to be moving relative to the fixed stars;
is a kind of celestial point
is a part of celestial sphere, empyrean, firmament, heavens, sphere, vault of heaven, welkin
Antonym: antapex
Derived form adjective apical1
1. The tip, top, point, or angular summit of anything; as, the apex of a mountain, spire, or cone; the apex, or tip, of a leaf. [1913 Webster]
2. The end or edge of a vein nearest the surface. [1913 Webster]
apex, abbr. Association of Professional, Executive, Clerical, and Computer Staff.
apex, n. (also APEX) (often attrib.) a system of reduced fares for scheduled airline flights when paid for before a certain period in advance of departure.
Etymology:
Advance Purchase Excursion
apex, n. (pl. apexes or apices)
1 the highest point.
2 a climax; a high point of achievement etc.
3 the vertex of a triangle or cone.
4 a tip or pointed end.
Etymology:
L, = peak, tip
N summit, summity, top, peak, vertex, apex, zenith, pinnacle, acme, culmination, meridian, utmost height, ne plus utra, height, pitch, maximum, climax, culminating point, crowning point, turning point, turn of the tide, fountain head, water shed, water parting, sky, pole, tip, tip top, crest, crow's nest, cap, truck, nib, end, crown, brow, head, nob, noddle, pate, capsheaf, high places, heights, topgallant mast, sky scraper, quarter deck, hurricane deck, architrave, frieze, cornice, coping stone, zoophorus, capital, epistyle, sconce, pediment, entablature, tympanum, ceiling, attic, loft, garret, house top, upper story, summit conference, summit, peak of achievement, peak of performance, peaks and troughs, peaks and valleys (in graphs), highest &c (high), top, top most, upper most, tiptop, culminating, meridian, meridional, capital, head, polar, supreme, supernal, topgallant, atop, at the top of the tree, en flute, fleur deau.