The website treehugger.com has identified a number of Celtic landscape terms that have no equivalent in English, including:
Ammit: The thin film of ice that lacquers all leaves, twigs and grass blades when a freeze follows a partial thaw, and that in sunlight can cause a whole landscape to glitter.
Fegdon: A small stream running from a moorland loch.
Pirr: A light breath of wind, such as will make a cat's paw on the water.
Smeuse: A gap in the base of a hedge made by the regular passage of a small animal.

Using the concept of lexicalization, explain why English and Celtic vocabularies differ in regard to these terms.