STEP Hebrew Lexicon: תֹּ֫הוּ

1) formlessness, confusion, unreality, emptiness

1a) formlessness (of primeval earth)

1a1) nothingness, empty space

1b) that which is empty or unreal (of idols) (fig)

1c) wasteland, wilderness (of solitary places)

1d) place of chaos

1e) vanity