In Brittany there are relatively few saints who are only honoured in a single location. St Nonne is one of these, inasmuch as her cult is only attested at Dirinon, in a parish which also honours her son Divi. St Nonne is the patron saint of a chapel and a fountain located just over a kilometre to the south of the market town. Although the cult of Divi was introduced in a number of other locations, there was not a similar veneration for his mother in Brittany.

It has been suggested that the saint should be seen as the eponym of the parish of Lennon; it cannot be established, however, whether the second element of the place-name is -non or -on. The church of Lennon is, at least since the sixteenth century, dedicated to the Holy Trinity. If in the case of the village of Lannon in Bannalec the possibility of an eponym in Nonn, associated with the old Breton lan (‘hermitage, monastery’) is excluded by the fact of the form Langoezen in 1491, it is, by contrast, indicated for the village of Lannon, in Kersaint-Plabennec, by the existence of the village of Lesnon, just over a kilometre to the south-west; the latter toponym is formed with the Old Breton les, ‘court, castle’.

The cult of St Nonne (Non) is better attested across the Channel. In Wales, where she is the eponym of three place-names in Llan-non, she had five chapels altogether.