From Wiktionary, the free dictionary
Compound of सिंह (siṃha, “chief”) + द्वार (dvāra, “doorway”).
सिंहद्वार • (siṃhadvāra) stem, n
- a gate, entrance, especially the chief gate of a mansion or palace
- Monier William's Sanskrit-English Dictionary, 2nd Ed. 1899.