hélicoïdal w języku angielskim

helical▼◼◼◼(in the shape of a helix)
adjective
[UK: ˈhe.lɪk.l̩] [US: ˈhe.lɪk.l̩]

helicoid▼◼◻◻(having the form of a flattened helix)
adjective
[UK: hˈelɪkˌɔɪd] [US: hˈelɪkˌɔɪd]