Im 2010, I completed the University of California San Diego Copyeditor Certification program, which had The Grammar Lab  as a prerequisite class. In order to go on in the course, we had to master the complex set of rules that govern word usage and punctuation.

Definitions of grammar on the Web:

  • the branch of linguistics that deals with syntax and morphology (and sometimes also deals with semantics)
    wordnetweb.princeton.edu/perl/webwn  
  • In linguistics, grammar is the set of logical and structural rules that govern the composition of sentences, phrases, and words in any given natural language. …
    en.wikipedia.org/wiki/Grammar  
  • A formal grammar (sometimes simply called a grammar) is a set of rules of a specific kind, for forming strings in a formal language. The rules describe how to form strings from the language’s alphabet that are valid according to the language’s syntax. …
    en.wikipedia.org/wiki/Grammar_(mathematics)  
  • A system of rules and principles for speaking and writing a language; The study of the internal structure of words (morphology) and the use of words in the construction of phrases and sentences (syntax); A book describing the rules of grammar of a language; A formal system specifying the …
    en.wiktionary.org/wiki/grammar
  • Grammar is the system of relationships between elements of the sentence that links the ‘sounds’ to the ‘meanings’. It is used to refer both to the knowledge of language in the speaker’s mind, and to the system as written down in rules, grammar-books and other descriptions. …
    homepage.ntlworld.com/vivian.c/Linguistics/LinguisticsGlossary.htm
  • searches through the italics (grammar info)
    polish.slavic.pitt.edu/~swan/beta/
  • A grammar is a set of rules which determine if a sequence of characters conform to a language. As used in the specification these rules are context-free.
    msdn.microsoft.com/en-us/library/dd285255.aspx 
  • a part of language comprised of both morphology and syntax, grammar allows an infinite expression of ideas, makes language itself possible, and may have been naturally selected for
    www.csa.com/discoveryguides/lang/gloss.php  
  • Not to be confused with socially correct usage. In order to handle novel sentences, we not only need to access the words stored in our brains but also the patterns of sentences possible in a particular language. These patterns describe not just patterns of words but also patterns of patterns. …
    williamcalvin.com/LEM/LEMend.htm
  • lie and prevaricate (synonyms); skillful and clumsy (antonyms); cow and bovine (noun to adjective). How to find the Correct Answer to the above puzzle? …
    www.vocabulary.com/VUwordanalogy.html
  • A set of rules that together define a language.
    oreilly.com/flex/excerpts/9780596155971/glossary.html
  • a formal description of a language in terms of vocabulary and rules for writing phrases and sentences.
    www.cs.utexas.edu/users/novak/cs315vocab.html
  • The system of rules by which words are formed and put together to make sentences.
    www.cpin.us/p/pel/glossary.htm
  • comes from the Greek word grammatikos, which is best translated “letters” and carries all the meanings of our word letters. Grammar cultivates the skill of interpreting symbols, first, individual letters or phonemes, then words, and ultimately texts, works of art, and artifacts.
    circeinstitute.org/definitions%202.shtml
  • [noun] Grammar is used to refer to a number of areas of knowledge: traditionally, the morphological and syntactic properties of a human language; a system of structural rules which are the basis of linguistic generation and understanding; a language theory or a model of linguistic competence. …
    portal.bibliotekivest.no/terminology.htm