Abbreviation

‘An abbreviation (from Latin brevis, meaning short) is a shortened form of a word or phrase, by any method. It may consist of a group of letters, or words taken from the full version of the word or phrase; for example, the word abbreviation can itself be represented by the abbreviation abbr., abbrv., or abbrev.; NBM, for nil (or nothing) by mouth is an abbreviated medical instruction. It may also consist of initials only, a mixture of initials and words, or words or letters representing words in another language (for example, e.g., i.e. or RSVP). Some types of abbreviations are acronyms (which are pronounceable), initialisms (using initials only), or grammatical contractions or crasis.

An abbreviation is a shortening by any of these, or other, methods.’

https://en.wikipedia.org/wiki/Abbreviation