also: ふるき
noun
Refers to a tree that has lived for many years, often with a sense of dignity or historical value.
神社の境内には大きな古木が立っている。
A large old tree stands in the shrine grounds.
この古木は樹齢五百年と言われている。
This old tree is said to be 500 years old.
老木 also means an old tree, but often emphasizes the aged, weathered appearance, while 古木 can simply mean an old tree without that nuance.
Compound of 古 (old) and 木 (tree). The reading こぼく is the on'yomi, while ふるき uses the kun'yomi of 古 and 木.