A cipher is a secret code, usually one that's created using a mathematical algorithm. Sometimes the message written in code is itself called a cipher.

Cipher comes from the Arabic sifr, which means "nothing" or "zero." The word came to Europe along with the Arabic numeral system. As early codes substituted numerals for letters to hide the word’s meaning, codes became known as ciphers. If you crack a cipher, you break the code and can understand the message. From its "zero" meaning, cipher can also be used for a person who has no influence or importance in the world.

Definitions of cipher
  1. noun
    a secret method of writing
    synonyms: cryptograph, cypher, secret code
    see moresee less
    type of:
    a coding system used for transmitting messages requiring brevity or secrecy
  2. noun
    a message written in a secret code
    synonyms: cypher
    see moresee less
    type of:
    a communication (usually brief) that is written or spoken or signaled
  3. verb
    convert ordinary language into code
    synonyms: code, cypher, encipher, encrypt, inscribe, write in code
    see moresee less
    type of:
    convert information into code
  4. noun
    a mathematical element that when added to another number yields the same number
    synonyms: 0, cypher, nought, zero
    see moresee less
    type of:
    digit, figure
    one of the elements that collectively form a system of numeration
  5. noun
    a quantity of no importance
    synonyms: aught, cypher, goose egg, nada, naught, nil, nix, nothing, null, zero, zilch, zip, zippo
    see moresee less
    (Latin) nil; nothing (as used by a sheriff after an unsuccessful effort to serve a writ)
    type of:
    relative quantity
    a quantity relative to some purpose
  6. noun
    a person of no influence
    synonyms: cypher, nobody, nonentity
    see moresee less
    pip-squeak, small fry, squirt
    someone who is small and insignificant
    jackanapes, lightweight, whippersnapper
    someone who is unimportant but cheeky and presumptuous
    type of:
    common man, common person, commoner
    a person who holds no title
  7. verb
    make a mathematical calculation or computation
    synonyms: calculate, compute, cypher, figure, reckon, work out
    work out
    be calculated
    see moresee less
    show 40 types...
    hide 40 types...
    quantise, quantize
    apply quantum theory to; restrict the number of possible values of (a quantity) or states of (a physical entity or system) so that certain variables can assume only certain discrete magnitudes that are integral multiples of a common factor
    calculate the root of a number
    perform mathematical and logical operations on (data) according to programmed instructions in order to obtain the required information
    divide or assess proportionally
    miscalculate, misestimate
    calculate incorrectly
    calculate anew
    average, average out
    compute the average of
    factor, factor in, factor out
    resolve into factors
    add, add together
    make an addition by combining numbers
    deduct, subtract, take off
    make a subtraction
    combine by multiplication
    divide, fraction
    perform a division
    extrapolate, interpolate
    estimate the value of
    calculate a derivative; take the derivative
    calculate the integral of; calculate by integration
    plot a map of (land)
    approximate, estimate, gauge, guess, judge
    judge tentatively or form an estimate of (quantities or time)
    make a budget
    capitalise, capitalize
    compute the present value of a business or an income
    resolve, solve
    find the solution
    raise to the second power
    raise to the third power
    foot, foot up
    add a column of numbers
    carry back
    deduct a loss or an unused credit from taxable income for a prior period
    multiply (a number) by itself a specified number of times: 8 is 2 raised to the power 3
    divide by two; divide into halves
    divide by four; divide into quarters
    survey by triangulation
    quantise, quantize
    approximate (a signal varying continuously in amplitude) by one whose amplitude is restricted to a prescribed set of discrete values
    gauge something incorrectly or improperly
    place, put, set
    estimate the duration or outcome of something
    lowball, underestimate
    make a deliberately low estimate
    estimate the value of (property) for taxation
    calculate as being
    count, reckon
    take account of
    overcapitalise, overcapitalize
    estimate the capital value of (a company) at an unreasonably or unlawfully high level
    factorise, factorize
    resolve (a polynomial) into factors
    approximate by ignoring all terms beyond a chosen one
    estimate based on a calculation
    type of:
    think logically
Word Family

Test prep from the experts

Boost your test score with programs developed by’s experts.

  • Proven methods: Learn faster, remember longer with our scientific approach.
  • Personalized plan: We customize your experience to maximize your learning.
  • Strategic studying: Focus on the words that are most crucial for success.


  • Number of words: 500+
  • Duration: 8 weeks or less
  • Time: 1 hour / week


  • Number of words: 500+
  • Duration: 10 weeks or less
  • Time: 1 hour / week


  • Number of words: 700+
  • Duration: 10 weeks
  • Time: 1 hour / week