| opaline |
like opal; opalescent. [2 definitions] |
| opaque |
not allowing light to pass through. (Cf. transparent.) [6 definitions] |
| op art |
a style of abstract, usu. hard-edged art in which forms, spaces, and colors are deliberately arranged to produce optical ambiguities and illusions. |
| op. cit. |
abbreviation of "opere citato" (Latin); in the work cited. |
| ope |
(archaic) to open. [2 definitions] |
| OPEC |
abbreviation of "Organization of Petroleum Exporting Countries." |
| op-ed |
a newspaper page, generally appearing opposite the editorial page, that presents the submitted opinions or contributions of readers, or a single signed article on such a page. [2 definitions] |
| open |
allowing entry or access; not shut, enclosed, or fastened. [27 definitions] |
| openable |
combined form of open. |
| open admissions |
the policy of admitting any student who desires to attend a university, regardless of proficiency. |
| open-air |
being, done, or occurring outdoors. |
| open air |
the outdoors. |
| open-and-shut |
(informal) not requiring much deliberation; not presenting ambiguity or difficulty; immediately obvious. |
| open chain |
in chemistry, a linear series of covalent atoms not joined at the ends into a cycle, such as an aliphatic compound. |
| open circuit |
an electrical circuit that is broken and carries no current. |
| open city |
a city in a war zone that is officially declared to be demilitarized and open to enemy occupation, and is thus rendered immune, by international law, to attack or bombardment. |
| open door |
free and unrestricted admission or access; unhindered opportunity. [2 definitions] |
| open-end |
lacking designated or agreed-upon limits. |
| open-ended |
not having fixed or set limits; unrestricted. [4 definitions] |
| opener |
someone or something that opens. [3 definitions] |
| open-eyed |
with the eyes open, esp. in amazement or wonder. [3 definitions] |