Facts may be compound or atomic. Atomic facts can't be rephrased as a conjunction of 2 or more smaller facts without information loss (with the same objects involved). Atomic facts are either elementary facts or existentail facts. Elementary facts apply a logical predicate to one or more objects, e.g.
The Country identified by the CountryCode 'US' is democratic (a unray fact);
The Politician named 'George W. Bush' is the preident of The Country identified by the CountryCode 'US' (a binary fact).
The Sportsman named 'Don Bradman' played the Sport named 'Cricket' for the Country identified by the CountryCode 'US' (a ternary fact).
Existential facts simply assert the existence of an object, e.g.
There exists a Country that is identified by the CountryCode 'US' .
Given an attribute set X and an attribute Y, X functionally determines Y iff for each instance of X there is at most one instance of Y.
There is an ORM symbol glossary in the library.
You will find a glossary of ORM terms in the back of Information Modeling and Relational Databases.