Apparently a masculine suffix attested in the name Dairon.
Doriathrin
* -os
suffix. abstract ending
* -on
suffix. masculine suffix
Beware, older languages below! The languages below were invented during Tolkien's earlier period and should be used with caution. Remember to never, ever mix words from different languages!
Apparently an abstract noun suffix appearing in the words Aros and thalos, perhaps of the same origin as the abstract endings ᴹQ. -sse² and N. -as, though Helge Fauskanger suggested instead that it is related to the locative suffix ᴹQ. -sse¹ (AL-Ilkorin/thalos).