'trellis' originates from Old French, specifically the word 'treillis', where it meant 'lattice'.

'trellis' changed from the Old French word 'treillis' and entered Middle English (as forms like 'treliss'), eventually becoming the modern English word 'trellis'.

Initially it meant 'lattice' (a framework of crossed strips); over time it retained this core sense while the verbal sense 'to provide with a trellis / to train on a trellis' developed from the noun.