The story
- Latin · derived fromtrichila“arbor", "summer house”
- Old French · derived fromtreille“arbor”
- Anglo-Norman · derived fromtreslis
- Middle English · inherited fromtrelis
- English todaytrellis
From Middle English trelis, from Anglo-Norman treslis, from Old French treille (“arbor”), from Latin trichila (“arbor", "summer house”). However, see OED which claims another Old French form referring to sackcloth, from Vulgar Latin.
Etymology from Wiktionary, CC BY-SA 4.0.