Betulah (H1330) is the standard Hebrew word for a virgin or unmarried young woman. It appears about 50 times in the OT and often carries the sense of purity and undefiled status. The lament over a destroyed city uses betulah as a metaphor for violated innocence.
Betulah is theologically significant in several contexts: marriage law (Deuteronomy 22), prophetic lament ('the virgin of Israel' — Amos 5:2), and eschatological hope (Joel 1:8; Revelation). While Isaiah 7:14 uses almah (young woman) for the Immanuel sign, betulah carries the clearer meaning of sexual purity, and the LXX's parthenos draws on both concepts.