There are 19 words that start with 'foi'.
foil | foin | foils | foins |
foist | foible | foiled | foined |
foison | foists | foibles | foiling |
foining | foisons | foisted | foilable |
foilsman | foilsmen | foisting | |
Note: These 19 words that start with 'foi' are found from the USA & Canada version of the tournament Scrabble word list.