1.  abbreviation(n = noun.communication) - a shortened form of a word or phrase;
is a kind of descriptor, form, signifier, word form
has particulars: apocope
Derived form verb abbreviate₂

2.  abbreviation(n = noun.act) - shortening something by omitting parts of it;
is a kind of shortening

1.  The act of shortening, or reducing. [1913 Webster]

2.  The result of abbreviating; an abridgment. Tylor. [1913 Webster]

3.  The form to which a word or phrase is reduced by contraction and omission; a letter or letters, standing for a word or phrase of which they are a part; as, Gen. for Genesis; U.S.A. for United States of America. [1913 Webster]

4.  One dash, or more, through the stem of a note, dividing it respectively into quavers, semiquavers, or demi-semiquavers. Moore. [1913 Webster]

abbreviation, n.
1 an abbreviated form, esp. a shortened form of a word or phrase.
2 the process of abbreviating.

N  compend, compendium, abstract, precis, epitome, multum in parvo, analysis, pandect, digest, sum and substance, brief, abridgment, summary, apercu, draft, minute, note, excerpt, synopsis, textbook, conspectus, outlines, syllabus, contents, heads, prospectus, album, scrap book, note book, memorandum book, commonplace book, extracts, excerpta, cuttings, fugitive pieces, fugitive writing, spicilegium, flowers, anthology, collectanea, analecta, compilation, recapitulation, resume, review, abbreviation, abbreviature, contraction, shortening, compression, compendious, synoptic, analectic, abrege, abridged, variorum, in short, in epitome, in substance, in few words, it lies in a nutshell.

N  shortness, brevity, littleness, a span, shortening, abbreviation, abbreviature, abridgment, concision, retrenchment, curtailment, decurtation, reduction, epitome, elision, ellipsis, conciseness, abridger, epitomist, epitomizer, short, brief, curt, compendious, compact, stubby, scrimp, shorn, stubbed, stumpy, thickset, pug, chunky, decurtate, retrousse, stocky, squab, squabby, squat, dumpy, little, curtailed of its fair proportions, short by, oblate, concise, summary, shortly, in short.