nasal sound change; hatsuonbin
Linguistics term for the historical sound change where a verb stem ending in 'i' or 'u' generates the moraic nasal 'n' (ん), as in 読みて → 読んで. Often contrasted with 促音便 (geminate sound change).
See also: 促音便
The 'n' in 'yonde' is an example of hatsuonbin.