D

/di:/
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Definition
  1. Noun:

    • The fourth letter of the modern English alphabet: "d" is a consonant and the fourth letter in the English alphabet.
    • The Roman numeral for 500: In the Roman numeral system, "D" represents the number five hundred.
    • A musical note: In the system of solfège, "D" is the note "re" and is the second note of the C major scale.
    • A shape or object resembling the letter D: Something that has the curved and straight form of the capital letter D.
  2. Adjective:

    • Denoting a quantity of 500: Used before a noun to specify an amount of five hundred units. (This usage is derived from its role as a Roman numeral).
Usage Examples
  • Noun:

    • The word "dog" starts with the letter d.
    • In Roman numerals, D equals 500.
    • The first string on the violin is tuned to D.
    • The carpenter used a D-ring to secure the strap.
  • Adjective:

    • The manuscript is from around D CCC (500 + 300 = 800) AD. (Note: This adjectival use is specific to numeral notation).
Advanced Usage
  • "D" as a grade: In academic grading systems in some countries, "D" often represents a below-average but passing grade.

    • He was disappointed to get a D in chemistry, but at least he passed.
  • "D" as a size or type: Used in product classifications, such as battery sizes (e.g., D-cell) or bra cup sizes.

    • This flashlight requires two D batteries.
  • "D" in physics: Can stand for specific quantities, such as "diffusion coefficient" or "electric displacement field," but these are specialized scientific symbols, not general uses of the word "d".

Variants and Related Words
  • D. (abbreviation): An abbreviation for titles like "Doctor" or "Drive" (as in a road).
    • The appointment is with D. Smith.
  • d. (abbreviation): An abbreviation for "died," "penny" or "pence" (in old British currency), or "day."
    • The inscription read: John Doe, b. 1920, d. 2005.
Synonyms
  • Five hundred: The cardinal number equivalent to the Roman numeral D.
  • Re: The solfège name for the musical note D.
Related Phrases
  • D-Day: A military term for the designated day an operation begins, now commonly used for any important day.
    • The project's D-Day is next Monday.
  • D-List: Referring to the lowest category of fame or celebrity.
    • After the scandal, the actor was relegated to the D-list.
Related Idioms
  • Mind your p's and q's: While not containing "d," this idiom about being careful with details is analogous to being careful with letters. A potential idiom involving "d" is less common, but one could say "from A to D" to imply a partial range or incomplete coverage, contrasting with the full "from A to Z."
    • His report only covered the topic from A to D, missing many key points.
Adjective
  1. denoting a quantity consisting of 500 items or units
Noun
  1. the 4th letter of the Roman alphabet
  2. the cardinal number that is the product of one hundred and five
  3. a fat-soluble vitamin that prevents rickets