Webster's Revised Unabridged Dictionary
Gr. a wheel + -oid,; cf. F. trochoïde,. See Troche
Chambers's Twentieth Century Dictionary
Gr. trochæidēs, round like a wheel—trochos, wheel, eidos, form.
Then any point in the circumference of the half-crown will move through a curve called a 'trochoid.
"Boating" by W. B. Woodgate
For epi- and hypo-cycloids and epi- and hypo-trochoids see EPICYCLOID.
"Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 8" by Various