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Webster 1828 Edition

[See Glen.]

glyn ‎(plural glyns)

A valley in a mountain area, especially one with a stream in the bottom
- Spenser
  He could not beat out the Irish, yet he did shut them up within those narrow corners and glyns under the mountain's foot.

From Proto-Brythonic *glɨnn, from Proto-Celtic *glendos.

glyn m (plural glynnoedd)

Welsh mutation
radical	soft	nasal	aspirate
glyn	lyn	nglyn	unchanged
Note: Some of these forms may be hypothetical. Not every possible mutated form of every word actually occurs.