Jolan and AB, thanks. It is a friendly discussion - and intriguing too.
I see now why you didn't want to disclose the origin of the clue. Good thinking.
But...to add to the *Saga*, the p(i)lot thickens! I looked it up and it's a French word, pilotis, meaning a set of piles, stilts or posts (Fr. pilots) supporting a building above the water or ground.
Pilotis is a singular word but it is also the plural form of the word.
In French:
pilotis
nom masculin invariant en nombre
(masculine noun invariable by number)
ensemble de pilots, de gros pieux supportant une construction
(an ensemble of stilts or posts, large stakes - pieux:originally wooden stakes - or posts supporting a building)
I'm guessing English speakers may have taken PILOTIS as if it were (solely) plural and made up a word PILOTI, which as they thought, would denote the singular! Maybe...I don't know.