Bunker
mid 16th century (originally Scots, denoting a seat or bench): perhaps related to bunk1.
wiktionary
The origin of the noun is uncertain; [1] the earliest sense is sense 6.1 (“box or chest, the lid of which serves as a seat”), from Scots bunker(“bench; pew; window-seat; sand pit (especially in golf); coal receptacle; sleeping berth, bunk”), probably from Old Norse bunki(“a heap”) (probably whence bunk(“sleeping berth in a ship, train, etc.”)), [2] [3] from Proto-Germanic *bunkô(“a heap, pile; a bump, lump, a crowd”), perhaps from Proto-Indo-European *bʰenǵʰ-(“thick”) or *bʰeg-(“to billow, swell; to arch, bend, curve (?)”). Sense 1 (“hardened shelter designed to protect the inhabitants from falling bombs or other attacks”) was derived from German Bunker during World War II, which was itself from bunker(“large bin or container for storing coal”)(sense 5).
The verb is derived from the noun. [4]
From bunk(“to fail to attend school or work without permission, to play truant”) + -er( suffix forming agent nouns indicating a person or thing that does an action).
Clipping of mossbunker, [5] a variant of mossbanker, from Dutch marsbanker(“common scad or Atlantic horse mackerel ( Trachurus trachurus)”), from Marsdiep(“deep tide-race between Den Helder and Texel in the Netherlands”) + bank(“shallow part of the sea near a coast”) + -er( suffix forming nouns denoting male inhabitants of a place).
etymonline
bunker (n.)
1758, originally Scottish, "seat, bench," a word of uncertain origin, possibly a variant of banker "bench" (1670s; see bank (n.2)); or possibly from a Scandinavian source (compare Old Swedish bunke "boards used to protect the cargo of a ship"). Meaning "receptacle for coal aboard a ship" is from 1839. Of sand-holes on golf courses, by 1824, from the extended sense "earthen seat" (1805). The meaning "dug-out fortification" probably is from World War I.
