'Tompion' definitions:

Definition of 'tompion'

noun

Plug for the muzzle of a gun to keep out dust and moisture [syn: tampion, tompion]

From: GCIDE

Tompion \Tom"pi*on\, n. [See Tampios]
1. A stopper of a cannon or a musket. See Tampion. [1913 Webster]
2. (Mus.) A plug in a flute or an organ pipe, to modulate the tone. --Knight. [1913 Webster]
3. The iron bottom to which grapeshot are fixed. [1913 Webster]

From: GCIDE

Tampion \Tam"pi*on\, n. [F. tampon, tapon, tape, of Dutch or German origin. See Tap a pipe or plug, and cf. Tamp, Tampop, Tompion.] [Written also tampeon, and tompion.]
1. A wooden stopper, or plug, as for a cannon or other piece of ordnance, when not in use. [1913 Webster]
2. (Mus.) A plug for upper end of an organ pipe. [1913 Webster]