diagram

Pluraldiagrams

Formsdiagrams, diagramming, diagrammed

1. 1
   nouncountable

   A drawing, plan, or sketch that shows how something works or how the parts of a whole relate to each other.

   The engineer sketched a diagram to explain how the cooling system moved heat away.

   Each chapter opens with a labeled diagram of the machine's internal parts.

   Similardrawing, sketch, plan, schematic, illustration

   Note

   The general sense came into English through French diagramme and Italian diagramma, from Greek diágramma. A diagram explains rather than depicts. It sits beside maps, photographs and statistical charts as a visual aid, but it is the one built to show structure or connection. It usually takes of before its subject (a diagram of molecular structure) or a field word in front (electrical diagrams).

2. 2
   nouncountable

   A graph or chart presenting data or numerical relationships in visual form.

   The report included a diagram tracking unemployment across the decade.

   Analysts presented a diagram of quarterly revenue beside the written summary.

   Similarchart, graph, figure

   Note

   Here the word overlaps with graph and chart, and it mostly appears with a qualifier naming the kind: a timing diagram, a scatter diagram, a sawtooth diagram. In such names the choice of word is loose, and scatter diagram, scatter graph and scatter plot are used interchangeably. Where the explanatory drawing shows how parts connect, this sense plots values, very often against time on the horizontal axis.

3. 3
   verbtransitive

   To represent or show something by means of a diagram.

   The consultant diagrammed the company's reporting structure for the new hires.

   Students learn to diagram complex sentences in grammar class.

   Similarmap, chart, sketch, outline

   Note

   The verb usually doubles its final m before an ending: diagrammed, diagramming. The single-m forms diagramed and diagraming exist but are rare, so the doubled spelling is the safe choice. It is transitive and takes the thing shown as its object: one diagrams a structure, a process, a sentence.

4. 4
   nouncountable

   The grid of white and blocked squares that forms a crossword puzzle.

   The setter designed a symmetrical diagram before writing any clues.

   Half the diagram was still empty when she got stuck on the long across answer.

   Similargrid

   Note

   Crossword books use this word for the grid itself, and pair it with entries, their name for the answers written into it. Stanley Newman's The Beginner's Crossword Dictionary (2019) pictures a completed diagram as a house: short words with common letters are the mortar that makes the longer brick words possible. Michelle Arnot's Crossword Puzzles For Dummies (1998) advises testing the 10- to 15-letter entries first.

5. 5
   verbUKtransitive

   To plan and assign the workings of a locomotive or train in line with a diagram.

   Controllers diagrammed the new electric units across the suburban routes.

   The roster clerk had to diagram each locomotive around its maintenance windows.

   Similarschedule

   Note

   A British railway term tied to the working diagrams that set out each engine's duties. The people who drew them up were timing and diagramming staff. In "Talking of trains" (Trains Illustrated, 1961), they produce engine, guards' and carriage working diagrams, so crews are diagrammed as well as rolling stock. The verb shares the doubled-m spelling of the general verb.

6. 6
   nouncountable

   A functor from an index category to another category, used to pick out a pattern of objects and morphisms that outlines part of the target category's structure.

   The proof hinges on a diagram whose index category has just two objects and a single morphism.

   The lecturer defined the limit as a universal cone over a diagram indexed by J in C.

   Note

   In category theory the word names a mapping, not a picture. The index category is pure scaffolding. Its objects and arrows carry no content of their own and only trace a shape onto part of the target category. Hence the standard phrasing a diagram of type J in C, which gives the shape first and the category it lands in second.

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