Chapter Optically to Orangeroot of O by Webster's Dictionary (1913 Edition)

Optometer
(Op*tom"e*ter) n. [Optic + -meter.] (Physiol.) An instrument for measuring the distance of distinct vision, mainly for the selection of eveglasses.

Opulence
(Op"u*lence) n. [L. opulentia: cf. F. opulence. See Opulent.] Wealth; riches; affluence. Swift

Opulency
(Op"u*len*cy) n. See Opulence. Shak.

Opulent
(Op"u*lent) a. [L. opulens, opulentus, fr. ops, opis, power, wealth, riches, perh. akin to E. apt: cf. F. opulent. Cf. Copious, Couple, Office.] Having a large estate or property; wealthy; rich; affluent; as, an opulent city; an opulent citizen. — Op"u*lent*ly, adv.

I will piece
Her opulent throne with kingdoms.

Shak.

Opuntia
(||O*pun"ti*a) n. [NL.] (Bot.) A genus of cactaceous plants; the prickly pear, or Indian fig.

Opus
(||O"pus) n.; pl. Opera [L. See Opera.] A work; specif. (Mus.), a musical composition.

Each composition, or set of pieces, as the composer may choose, is called an opus, and they are numbered in the order of their issue. (Often abbrev. to op.)

Opus incertum. [L.] (Arch.) See under Incertum.

Opuscle
(O*pus"cle O*pus"cule) n. [L. opusculum, dim. of opus work: cf. F. opuscule.] A small or petty work.

Opusculum
(||O*pus"cu*lum) n.; pl. Opuscula [L.] An opuscule. Smart.

Opye
(O"pye) n. Opium. [Obs.] Chaucer.

Oquassa
(O*quas"sa) n. (Zoöl.) A small, handsome trout found in some of the lakes in Maine; — called also blueback trout.

- or
(-or). [L. -or: cf. OF. -or, -ur, - our, F. -eur.]

1. A noun suffix denoting an act; a state or quality; as in error, fervor, pallor, candor, etc.

2. A noun suffix denoting an agent or doer; as in auditor, one who hears; donor, one who gives; obligor, elevator. It is correlative to - ee. In general -or is appended to words of Latin, and - er to those of English, origin. See -er.

Or
(Or) conj. [OE. or, outher, other, auther, either, or, AS. awer, contr. from ahwæer; a aye + hwæer whether. See Aye, and Whether, and cf. Either.] A particle that marks an alternative; as, you may read or may write, — that is, you may do one of the things at your pleasure, but not both. It corresponds to either. You may ride either to London or to Windsor. It often connects a series of words or propositions, presenting a choice of either; as, he may study law, or medicine, or divinity, or he may enter into trade.

If man's convenience, health,
Or safety interfere, his rights and claims
Are paramount.

Cowper.

Or may be used to join as alternatives terms expressing unlike things or ideas (as, is the orange sour or sweet?), or different terms expressing the same thing or idea; as, this is a sphere, or globe.

Or sometimes begins a sentence. In this case it expresses an alternative or subjoins a clause differing from the foregoing. "Or what man is there of you, who, if his son shall ask him for a loaf, will give him a stone?" Matt. vii. 9 (Rev. Ver. ).