titer

noun

ti·​ter ˈtī-tər 

variants or chiefly British titre

plural titers

1

: the strength of a solution or the concentration of a substance in solution as determined by titration

… if the analyst is using an oxalic acid solution to titrate a solution of calcium oxide, the titer of the oxalic acid solution would be expressed as its CaO titer, or the weight of CaO that is consumed by 1mL of the oxalic acid solution.

—John Kenkel

2

: a measure of the concentration of a substance (such as an antibody) in a blood sample that is obtained by subjecting the sample to serial dilutions (as with saline) to determine the maximum dilution at which the sample retains a specific activity (such as neutralizing an antigen) and that is often expressed as a ratio (such as 1:200)

I have examples of people who clearly were infected who are antibody negative. They probably have such a low titer of antibody that it's below the level of the cutoff.

—Anthony Fauci

The Blood Center will also ensure that the plasma has high titers of antibodies against the coronavirus.

—John Timmer

also : a test for obtaining a blood titer

—often used before another noun

an antibody titer test

Examples of titer in a Sentence

Recent Examples on the Web

This is why antibody and titer tests should be used only in specific cases, in consultation with your doctor. —Daniel Pastula, The Conversation, 19 Mar. 2025

The commercial laboratory tests or titer tests are most useful for people who don’t know their vaccination status, experts say. —Neha Mukherjee, CNN, 13 Feb. 2025

Antibody titers in vaccinated condors — a gauge of their immunity — are being monitored, and the results will inform future vaccination plans, the spokesperson added. —Karen Kucher, Mercury News, 24 Mar. 2025

Other crucial elements of your immune response include B cells, T cells and other immune cells, but a titer test does not show their capabilities. —Daniel Pastula, The Conversation, 19 Mar. 2025

Word History

Etymology

French titre title, proportion of gold or silver in a coin, from Old French title inscription, title

First Known Use

1861, in the meaning defined at sense 1

Rhymes for titer

• biter
• brighter
• fighter
• lighter
• miter
• niter
• reiter
• righter
• slighter
• tighter
• titre
• whiter

Medical Definition

titer

noun

ti·​ter ˈtīt-ər 

variants or chiefly British titre

ˈtī-tər also ˈtē-

1

a

: the strength of a solution or the concentration of a substance in solution as determined by titration

b

: a measure of the concentration of a substance (such as an antibody) in a blood sample that is obtained by subjecting the sample to serial dilutions (as with saline) to determine the maximum dilution at which the sample retains a specific activity (such as neutralizing an antigen) and that is often expressed as a ratio

a test for toxoplasmosis antibodies yielded a titer of 1:1024

Children with rash had higher antibody titers than those without rash …

—Anne A. Gershon et al., The Journal of the American Medical Association

also : a test for obtaining a blood titer

—often used before another noun

an antibody titer test

2

: the solidifying point of the fatty acids liberated from a fat that is determined by melting the acids in a tube and noting the temperature at which they solidify again on cooling

titered

-ərd 

adjective