日本語道場 — Nihongo Dojo

～ともなく

~to mo naku / ~to mo nashi ni

without particular intention

When to use it

Use ～ともなく when describing an action done absent-mindedly, with no real intention or focus — typically perception verbs (見る・聞く・考える). In writing it lends a literary, reflective tone, so it appears in narrative passages, essays and the descriptive parts of reports rather than in direct business speech. The related pattern 疑問詞＋から／ともなく (誰からともなく, どこからともなく) means "from no particular source", which is common even in fairly neutral written business Japanese.

Formation

Verbs: dictionary form + ともなく／ともなしに（見るともなく、聞くともなしに）。Very often the same verb is repeated: 見るともなく見る。
Question words: 疑問詞＋（助詞）＋ともなく（誰からともなく、どこからともなく、いつからともなく）。
i-adjectives / na-adjectives / nouns: not used. (Do not confuse with the concessive ～とも/～ともあろう.)
Register: ともなしに is the more literary variant; ともなく is the standard written form.

Examples

Applause broke out from no one in particular, and the meeting ended.
The director half-listened to my report without really taking it in.
Rumours of a price hike spread through the company from nowhere in particular.
Staring blankly at the email on screen, I thought about my reply.
At some point or other, this practice had become established.