An abbreviation 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.; NPO, for nil per (by) os (mouth) is an abbreviated medical instruction. Unlike English, which is moving away from periods in abbreviations in some style guides, the placement of capital letters and periods is important in German . Current (I) — The flow of an electric An electric current can be compared to the flow of water in a pipe.