Abarim Publications' online Biblical Hebrew Dictionary
The substantive תוך (tawek) means midst and appears to be an exclusive Hebrew invention. It's unclear where it came from and it's not found in cognate languages.
Our word is used to indicate the middle element(s) of a set (Judges 16:29) or the middle or heart of a general area (Joshua 8:22, Isaiah 66:17) or phenomenon (Genesis 1:6). It's used in a general sense meaning "among" (Genesis 40:20) or "between" (Exodus 39:25). It's this word that YHWH used to describe his presence in Israel by means of the tabernacle (Exodus 25:8).
This word's sole derivative is the adjective תיכון or תיכן (tikon), meaning middle (Exodus 26:28, Judges 7:19, 1 Kings 6:6).