For @B00745@, the tendency of a compound to act as @H02904@ (@P04906@) acceptor. The basicity of a @CT01038@ is normally expressed by the @A00079@ of the conjugate acid (see @C01266@). For Lewis bases it relates to the @A00472@ constants of @L03510@ and @A04388@.
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1088 [Terms] [Paper]