Transylvania

wiktionary

ref

From trans-(“Latin trans, meaning across”) +‎ sylvan(“Latin silvam, the accusative singular of silva, meaning forest”) +‎ -ia(“meaning country, land”). (Meaning "region across the forest")

etymonline

ref

Transylvania

literally "beyond the forest," from Medieval Latin, from trans "beyond" (see trans-) + sylva (see sylvan). So called in reference to the wooded mountains that surround it.