Emily Dickinson Lexicon

HELM, or HEL'MET, n. [Sax. helm. See Helm.]

1. Defensive armor for the head; a head-piece; a morion. The helmet is worn by horsemen to defend the head against the broad sword.
2. The part of a coat of arms that bears the crest. Johnson.
3. The upper part of a retort. Boyle.
4. In botany, the upper lip of a ringent corol. Martyn.