bʰerǵ-
“to hide, to protect”hide, protect, shelter
Root for hiding/protecting, yielding English bury, borough, German Berg (mountain), Burg (fortress).
Discussion
The PIE root *bʰerǵ- (to hide, to protect, to keep safe by concealing) produced the Germanic vocabulary of burial, shelter, and mountain refuge — all aspects of the fundamental act of putting something out of sight for safekeeping.
German bergen (to rescue, to salvage, to hide) preserves the root most transparently: Bergung (a rescue operation), Geborgenheit (the feeling of being safe and sheltered — one of German's famously untranslatable emotional concepts), and the compound Eisberg (ice-mountain, iceberg — a mountain of ice that hides most of its mass below the surface).
English bury (OE byrgan, "to hide in the earth, to inter") continues the root with the specific sense of concealing in the ground. The related English borough (OE burg/burh, "a fortified place" — a settlement hidden behind walls) gave the -bury/-borough/-burgh suffixes in English place names: Canterbury, Edinburgh, Salzburg, Hamburg, Pittsburgh. A borough is etymologically a hiding-place, a refuge.
English burglar (from Medieval Latin burgulātor, one who breaks into a burg/fortress) descends from the same root — the burglar violates the protection that the burg provides.
Old Norse bjarg (rock, cliff — a natural hiding-place) and the related berg (mountain) show the Scandinavian extension to natural landscape features: a mountain IS a shelter, a cliff IS a wall.
The root's connection to both burial (hiding the dead) and fortification (hiding the living) reveals a conceptual unity: protection IS concealment. To be safe is to be hidden — behind walls (*bʰerǵ- → burg), under earth (*bʰerǵ- → bury), or within mountains (*bʰerǵ- → berg). The PIE speakers who named the act of hiding generated the vocabulary of both cemeteries and castles.
Notes
Pokorny 145. English bury, borough, Hamburg, iceberg, burglar.