Semantic knowledge is to use a Kantian label, synthetic apriori knowledge. Mature users of a language know the meaning of terms in their own language and thereby what the terms mean in any language into which their language is translated. Humans have insight into universal semantics. This knowledge is synthetic because in fact terms need not have the meaning they actually have. The terms could in fact have no meaning whatsoever. The knowledge is apriori because people know, at least implicitly, what their terms mean prior to using them in any particular situation. Perhaps, it would be more accurate to claim that people’s knowledge of the meaning of their terms is mostly expressed as negative knowledge. People know how to reject proposed definition of terms when those definitions fail to express what they mean. Socrates’ accusation that people do not know what they mean with crucial terms when they discover, with Socrates’ aid, that proposed definitions are either too broad or too narrow is inaccurate. People’s knowledge of the meaning of terms is a presupposition for recognizing definitions as too broad or too narrow for expressing what they mean.