Abarim Publications' online Biblical Hebrew Dictionary
The root-verb חדר (hadar), meaning to surround, is used only once in the Bible. The prophet Ezekiel speaks of an enigmatic sword "for the great one, which surrounds them" (Ezekiel 21:14). This verb's sole derivative, the masculine noun חדר (heder), meaning inner chamber, occurs much more often:
The noun חדר (heder) describes an intimate, innermost chamber, which provides seclusion and safety (Genesis 43:30, Joel 2:16, Isaiah 26:20). That the Hebrew language reserves a special word for this private room shows that social life in Biblical times offered much less privacy than it does today. It's probably safe to conclude that most people had no such heder, and rarely enjoyed a quiet moment alone.