The husk and stray are counted as sub-variants of existing mobs as opposed to entirely new mobs, hence why you are unable to simply type /summon Stray or /summon Husk. There was supposed to be spawn eggs for them, but it seems they were removed either intentionally or by accident in the final release.
Axiomatic method, in logic, a procedure by which an entire system (e.g., a science) is generated in accordance with specified rules by logical deduction from certain basic propositions (axioms or postulates), which in turn are constructed from a few terms taken as primitive.
For the term in algebraic geometry, see Postulation (algebraic geometry). An axiom or postulate is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Greek axÃ­Åma (á¼Î¾Î¯ÏÎ¼Î±) 'that which is thought worthy or fit' or 'that which commends itself as evident.'.