cabinet (n.)
1540s, "secret storehouse, treasure chamber," from Middle French cabinet "small room" (16c.), diminutive of Old French cabane "cabin" (see cabin); perhaps influenced by (or rather, from) Italian gabbinetto, diminutive of gabbia, from Latin cavea "stall, stoop, cage, den for animals" (see cave (n.)).

Meaning "case for safe-keeping" (of papers, liquor, etc.) is from 1540s, gradually shading to mean a piece of furniture that does this. Sense of "private room where advisors meet" (c.1600) led to modern political meaning (1640s); perhaps originally short for cabinet council (1630s); compare board (n.1) in its evolution from place where some group meets to the word for the group that meets there.