- incidentally, accidentally, by chance - in an incidental manner; "these magnificent achievements were only incidentally influenced by Oriental models"
- perchance, by chance - through chance, "To sleep, perchance to dream.."
- haply, by chance, by luck - by accident; "betrayed by a word haply overheard"
- by chance, accidentally, circumstantially, unexpectedly - without advance planning; "they met accidentally"