English Words: O
15,494 words · Page 305 of 310
The change in rate of oxygen consumption in the presence of varying oxygen levels in the environment.
A radical containing ferryl iron and an oxygen atom Feᴵⱽ-O; found especially in forms of heme
The chemical element (symbol O) with an atomic number of 8 and relative atomic mass of 15.9994. It is a colorless and odorless gas. Sometimes called elemental oxygen to distinguish it from molecular oxygen.
An event during the oxygenation event of Earth's past, where the level of free oxygen in the environment exceeds the tolerance levels of most extant anaerobic life.
The monitoring of the concentration or partial pressure of oxygen in the respiratory gases.
The form of haemoglobin, loosely combined with oxygen, present in arterial and capillary blood.
Any anion (and corresponding salt) in which a central atom is bonded to both oxygen and a halogen
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 305. 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.