Grammar as a phenomenon – a subsystem of language as a linguistic discipline

Function(Syntactic criterion/ properties)
Syntactic properties of a class of words are the combinability of words (the distributional criterion) and typical functions in the sentence.
The three criteria of defining grammatical classes of words in English may be placed in the following order: meaning, form and function.
Function:

• 
  Distributional subcriterion- combinability of words
  
• 
  Syntactic function proper – typical syntactic function ( Noun - , Verb- , Adj- etc)
  

A Part of Speech is a grammatically relevant class of words which is specified on the basis of grammatical , semantic and lexical properties. -> P.of Sp. Are lexico-grammatical categories.
A part of speech as a field structure + the scheme of the field structure
Parts of speech are heterogeneous classes and the boundaries are not clearly cut especially in the area of meaning. Within a part of speech there are subclasses which have all the properties of a given class and subclasses which have only some of these properties and may have features of another class. So a part of speech may be described as a field which includes both central, most typical members, and marginal, less typical members. Marginal areas of different parts of speech may overlap and there may be intermediary elements with contradictory features (statives, modal words, pronouns). Words belonging to different parts of speech may be united by a common feature and constitute a class cutting across other classes (for example, determiners). So the part-of-speech classification involves overlapping criteria and scholars single out from 9 to 13 parts of speech in Modern English.
Example in the copybook
Substantivized adjectives – the wise, the cold
Adjectivized nouns – stone wall
Alongside of the three-criteria principle of dividing words into grammatical classes there are classifications based on one principle, morphological or syntactico- distributional. (one – criterion classifications)