This SAE Aerospace Information Report (AIR) provides definitions for terms commonly used in aircraft inflight icing system design and analysis@ research@ and operations. Some general thermodynamic terms are included that are frequently used in icing analysis@ but this document is not meant to be an inclusive list of such terms. Purpose: The purpose of this document is to provide an assemblage of definitions for terms commonly used in aircraft icing. Over time@ the field of aircraft icing has evolved a set of terms that are sometimes used in different ways and have different meanings. This document is a compendium of icing terms and their associated definitions. The SAE does not endorse or recommend any particular definition given in this report.