An assay is a breakdown of a material, examining the individual parts that make up the whole. When you assay a situation, you look at all the elements that created the problem in order to come up with a solution.

The word assay comes from the French word essai, which means "trial," an appropriate sense for a word that means to examine for analysis. As a noun, assay means a test or appraisal to determine the components of a substance or object. As a verb, it refers to the act of analyzing, or of conducting that test. It is usually used in chemistry-related fields like metallurgy and pharmaceuticals, but you can also assay a poem.

Definitions of assay
  1. noun
    a quantitative or qualitative test of a substance (especially an ore or a drug) to determine its components; frequently used to test for the presence or concentration of infectious agents or antibodies etc.
    see moresee less
    show 19 types...
    hide 19 types...
    ELISA, enzyme-linked-immunosorbent serologic assay
    an assay that relies on an enzymatic conversion reaction and is used to detect the presence of specific substances (such as enzymes or viruses or antibodies or bacteria)
    an assay that shows specific antigens in tissues by the use of markers that are either fluorescent dyes or enzymes (such as horseradish peroxidase)
    diagnostic assay, diagnostic test
    an assay conducted for diagnostic purposes
    bio-assay, bioassay
    appraisal of the biological activity of a substance by testing its effect on an organism and comparing the result with some agreed standard
    immunoassay, immunochemical assay
    identification of a substance (especially a protein) by its action as an antigen
    examination of tissues or liquids from the living body to determine the existence or cause of a disease
    cloze procedure, cloze test
    a test for diagnosing reading ability; words are deleted from a prose passage and the reader is required to fill in the blanks
    faecal occult test, fecal occult test, stool test
    a test performed at home in which you collect specimens of your stool that are tested for traces of blood; used to detect colorectal cancers
    GI series
    diagnostic tests of the alimentary canal; usually involves inserting a contrast medium (such as barium sulfate) and taking an X-ray
    glucose tolerance test
    test of the body's ability to metabolize carbohydrates; used in the diagnosis of hypoglycemia and diabetes mellitus
    Pap test, Papanicolaou test, smear test
    a method of examining stained cells in a cervical smear for early diagnosis of uterine cancer
    PKU test
    a test of newborn infants for phenylketonuria
    pregnancy test
    a physiological test to determine whether a woman is pregnant
    Queckenstedt's test
    a test to determine whether there is a blockage of the spinal canal
    radioactive iodine test
    test of thyroid function in which the patient is given an oral dose of radioactive iodine-131
    Rubin test
    test to determine the patency or occlusion of the Fallopian tubes
    skin test
    any test to determine immunity or sensitivity to a disease by introducing small amounts on or into the skin
    tissue typing
    a series of diagnostic tests before an organ transplant to determine whether the tissues of a donor and recipient are compatible
    vital capacity
    the maximum amount of air that can be exhaled after a maximum inhalation (usually tested with a spirometer); used to determine the condition of lung tissue
    type of:
    run, test, trial
    the act of testing something
  2. noun
    a substance that is undergoing an analysis of its components
    see moresee less
    type of:
    a particular kind or species of matter with uniform properties
  3. noun
    a written report of the results of an analysis of the composition of some substance
    see moresee less
    type of:
    report, study, written report
    a written document describing the findings of some individual or group
  4. noun
    an appraisal of the state of affairs
    “they made an assay of the contents”
    synonyms: check
    see moresee less
    show 5 types...
    hide 5 types...
    countercheck, double check
    something that checks the correctness of a previous check
    Apgar score
    an assessment of the physical condition of a newborn infant; involves heart rate and muscle tone and respiratory effort and color and reflex responsiveness
    paternity test
    a test based on blood groups to determine whether a particular man could be the biological father of a particular child; negative results prove he was not the father but positive results show only that he could be
    stress test
    a test measuring how a system functions when subjected to controlled amounts of stress
    treadmill test
    a stress test in which the patient walks on a moving treadmill while the heart and breathing rates are monitored
    type of:
    appraisal, assessment
    the classification of someone or something with respect to its worth
  5. verb
    analyze (chemical substances)
    see moresee less
    subject to a bio-assay
    type of:
    analyse, analyze, canvas, canvass, delve, examine, parse, study
    consider in detail and subject to an analysis in order to discover essential features or meaning
  6. verb
    make an effort or attempt
    synonyms: attempt, essay, seek, try
    see moresee less
    show 17 types...
    hide 17 types...
    pick up the gauntlet, take a dare
    be dared to do something and attempt it
    fight, struggle
    make a strenuous or labored effort
    give it a try, have a go
    make an attempt at something
    search blindly or uncertainly
    endeavor, endeavour, strive
    attempt by employing effort
    give it a try, give it a whirl
    adventure, chance, gamble, hazard, risk, run a risk, take a chance, take chances
    take a risk in the hope of a favorable outcome
    lay on the line, put on the line, risk
    expose to a chance of loss or damage
    strive, struggle
    exert strenuous effort against opposition
    drive, labor, labour, push, tug
    strive and make an effort to reach a goal
    behave awkwardly; have difficulties
    be at pains, take pains
    try very hard to do something
    to strive with determination
    go for broke
    risk everything in one big effort
    luck it, luck through
    act by relying on one's luck
    adventure, hazard, jeopardize, stake, venture
    put at risk
    bell the cat
    take a risk; perform a daring act
    type of:
    act, move
    perform an action, or work out or perform (an action)
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