different generation; separation of ages; being of a different era
Refers to something that spans or is separated by a generation or era. Often used in fixed compounds such as 隔世遺伝 (atavism) or 隔世の感 (a feeling of being from another age).
Looking at my grandfather's memento gives me a feeling of a bygone era.
Through atavism, he looks exactly like his great-grandfather.
atavism; throwback; reappearance of an ancestral trait
Compound of 隔 (separate, gap) and 世 (world, generation, age). The exact historical derivation is uncertain, but the meaning 'separated by a generation/age' is transparent from the kanji.