without thinking; unconsciously; somehow
Used after a volitional verb form (e.g., 見るともなしに) to indicate doing something without clear intention or awareness. Often implies a vague, half-conscious action.
See also: ともなく
I was looking out the window without really paying attention, and then I noticed a stranger standing in the garden.
I was half-listening to the radio when a nostalgic song came on.
Derived from the particle と (quotative) + も (inclusive) + 無し (negative of ある) + に (adverbial particle). Literally 'without even saying/thinking that', it grammaticalized into a set phrase meaning 'without particular intention'.