Unusual cordial, mostly found in the West Indies. It tastes of lime, vanilla, ginger, almond, and other spices. So, if you want to substitute Falernum, use orgeat syrup, lime juice, and vanilla. And/or improvise.
Dark Rum of Jamaican Type, Overproof Rum, Falernum, Lime Juice, Orange Juice, Bitters, Grenadine
Light Rum, Lemon Juice, Falernum, Orange
Bourbon, Cherry Brandy, Fernet Branca, Falernum, Lime Juice