batten
n.
"strip of wood (especially used to fasten canvas over ships' hatches)," 1650s, anglicized variant of baton "a stick, a staff" (see baton). Nautical use attested from 1769.
v.
1
"to improve; to fatten," 1590s, probably representing an English dialectal survival of Old Norse batna "improve" (cognates: Old English batian, Old Frisian batia, Old High German bazen, Gothic gabatnan "to become better, avail, benefit," Old English bet "better;" also see boot, v.). Related: Battened; battening.
2
"to furnish with battens," 1775, from batten, n.; phrase batten down recorded from 1823. Related: Battened; battening.