Old or aged (referring to things, not people); worn or antique due to long existence or use.
この古い時計は祖父からもらった。
I received this old clock from my grandfather.
古い建物は耐震性が低いことがある。
Old buildings can sometimes have poor earthquake resistance.
保存状態が良ければ、古い本でも読むことができる。
If it's well preserved, even an old book can still be read.
Having existed for a long time; long-established or time-honored (often used as 古くから).
この祭りは古くから続いている。
This festival has been held since long ago.
古くからの習慣が今も残っている村だ。
It's a village where time-honored customs still remain.
古くより人々は星を観測してきた。
People have observed the stars since ancient times.
Belonging to the distant past; long-ago (referring to ancient times or events).
古い伝説がこの島に伝わっている。
An ancient legend has been passed down on this island.
その話は古い昔のことだ。
That story is from long ago.
古い時代の遺跡を発掘した。
They excavated ruins from an ancient era.
Stale, hackneyed, or trite; lacking freshness (used for overused expressions, jokes, ideas, etc.).
その冗談は古いから、もう笑えない。
That joke is old, so it's no longer funny.
記事は古い表現ばかりで新鮮味がない。
The article is full of stale expressions and lacks freshness.
その映画は古いプロットで先が読めてしまう。
That movie has a tired plot that's easy to predict.
Old-fashioned or outmoded; not up-to-date in style, ideas, or technology.
その服は古いので、今の流行には合わない。
That clothing is old-fashioned and doesn't fit current trends.
古い価値観は時代遅れだと言われることがある。
Old-fashioned values are sometimes called out as outdated.
このシステムは古い設計で改善が必要だ。
This system has an outdated design and needs improvement.