Emily Dickinson Lexicon

A'PEX, n. [plur. Apexes. L. apex, plur. apices.]

The tip, point, or summit of any thing. In antiquity, the cap of a flamen or priest; the crest of a helmet. In grammar, the mark of a long syllable. In botany, the anther of flowers, or tops of the stamens, like knobs. – Martyn.