English Words: O

15,494 words · Page 101 of 310

onbeatnoun

The first and third beats in a bar of four-four time.

onbeianoun

An elephant's tusk trumpet.

onboardadj

Carried or used on or in a vehicle or vessel.

onboardingnoun

(business) The process of bringing a new employee on board, incorporating training and orientation.

onbringingnoun

A bringing on; an oncome; inducing; induction.

onceadv

One and only one time.

once a man, twice a childproverb

A man is born as a child, grows to adulthood, and consequently enters old age, when he deteriorates and reverts to a childlike state.

once a woman, twice a childproverb

A woman is born as a child, grows to adulthood, and consequently enters old age, when she deteriorates and reverts to a childlike state.

once againadv

Again, once more, one more time.

once an adult and twice a childproverb

Alternative form of once an adult, twice a child.

once an adult, twice a childproverb

One is born as a child, grows to adulthood, and consequently enters old age, when one deteriorates and reverts to a childlike state.

once and for alladv

Conclusively, finally, permanently.

once in a blue moonadv

Very rarely; very infrequently.

once in a purple moonadv

Extremely rarely; almost never.

once in a wayadv

Once in a while; occasionally; every now and then.

once in a whileadv

Occasionally; sometimes.

once moreadv

Again, a further time, once again.

once more into the breachphrase

Let's get back to work.

once on a timeadv

once upon a time

once or twicephrase

A small, indefinite number of times.

once removedadj

One generation apart.

once upon a timeadv

A long time ago; at some time in the past (a traditional beginning of children's stories, especially fairy tales).

once you go blackphrase

Once a person of another race has a sexual relationship with a black person, implying that they will not return to having sexual relationships with members of the former race.

once you go black, you never go backproverb

Once someone has had sexual intercourse with a black person they will not want to return to having sexual intercourse with nonblack people.

once-in-a-generationadj

Very rare; likely to happen only once in a given generation.

once-in-a-lifetimeadj

Likely to happen only once in one's lifetime; extremely rare.

once-offadj

Alternative form of one-off.

once-overnoun

A quick clean or polish.

oncenessnoun

The state or condition of being once; singularity.

oncernoun

A one-pound note.

oncetadv

Once.

Onceștiname

A village in Mogoș, Alba County, Romania.

onchnoun

Alternative form of ankh.

onchocerciasisnoun

A disease caused by a worm of the genus Onchocerca, especially as transmitted to humans by flies and often causing blindness; common in tropical Africa.

onchocercomanoun

A nodule containing Onchocerca in river blindness (onchocerciasis).

onchocercomatanoun

plural of onchocercoma

onchsnoun

plural of onch

oncidiumnoun

Any of the genus Oncidium of tropical orchidaceous plants.

oncillanoun

A small spotted felid, of species Leopardus tigrinus, found in the tropical rainforests of Central America and South America.

onco-prefix

Pertaining to tumors.

oncoapoptosisnoun

The apoptosis of cancer cells, especially when induced therapeutically

oncoapoptoticadj

Relating to oncoapoptosis.

oncobiologynoun

The biology of cancer

oncocytenoun

A large, granular cell, having many mitochondria, found in salivary and certain endocrine glands.

oncocyticadj

Of or pertaining to an oncocyte or to oncocytoma

oncocytomanoun

A benign tumour composed of oncocytes.

oncodermatologynoun

The study and the treatment of skin disorders that are the result of cancer

oncodevelopmentaladj

Relating to the development of a cancer

oncodiabetologynoun

The study of the relationship between cancer and diabetes

oncodomainnoun

A protein domain responsible for a cancer

Spelling & Dictionary Insight

The English alphabetical index for the letter O contains 15,494 headwords drawn from our Wiktionary-derived dictionary table. At 50 entries per page the browse splits into 310 pages, and you are currently viewing page 101. Every row above is a dictionary-backed entry with a canonical slug, and each links through to a full definition page with pronunciation, senses, etymology, and related-word data where available.

On this page 50 of 50 entries carry a part-of-speech tag and 50 carry at least one stored definition. Coverage varies across letters because Wiktionary volunteers build entries at different speeds for different parts of the alphabet, letters with common starting sounds (S, C, T, P) usually have the densest coverage, while less frequent starters (X, Q, Z) tend to have shorter but more specialised lists. PlainSpell surfaces whatever data is present and links back to the source when a definition is not yet recorded.

For readers using this index as a spelling reference, the guarantee is that every form you see on the list is a documented English headword, not a guess, not a derived inflection lacking a lemma row. If a word you expected to find is absent from the "O" list, it usually means the form exists only as an inflection of another lemma (e.g. a past participle stored under the infinitive) or the entry has not yet been imported from Wiktionary. Use the search bar or the misspelling lookup to resolve these cases.