old times, old things, old friend, former, ex-
旧 centers on the past: old times, old things, or a former state. It applies to anything that is no longer current, including ex-relationships and old friends.
旧 is the modern simplified form of 舊. The older form is complex and unrelated to the modern components; the simplification replaced it with a new shape that visually suggests something old or worn.
The left vertical stroke looks like a worn-down edge, and the right side is 日 (day). Picture an old calendar where the days are marked off one by one, leaving a worn, aged appearance.
For キュウ, imagine an old, dusty cue ball in a pool hall: cue -> キュウ, and the ball is so old it's practically an antique.
old; former; ex-
restoration; restitution; rehabilitation
new and old; incoming and outgoing
old work; existing work
old friend; old pal
traditional; from ancient times; formerly
old type; old style
old promise; old agreement; old covenant
Japan's old (lunisolar) calendar
one's original family name; maiden name
old model; old type; old style
old state of affairs
old friend; old acquaintance
old edition
old road
Paleolithic; Palaeolithic; Old Stone Age
former name; maiden name
old family; old-established family
old system; old order
Bon Festival of the lunar calendar