| optimistic |
expecting or tending to expect favorable outcomes. [2 definitions] |
| optimize |
to make the most effective use of (something), or to make as effective, perfect, or well-functioning as possible. |
| optimum |
the situation, quantity, degree, or other condition that is most desirable. [2 definitions] |
| option |
the right, power, or freedom to choose. [4 definitions] |
| optional |
not required; left to one's choice. |
| optoelectronic |
of or relating to electronic devices that are powered by light or produce light from electricity, or to the study of such devices. |
| optoelectronics |
electronic devices that are powered by light or that produce light from electricity. [2 definitions] |
| optometrist |
one who practices optometry. |
| optometry |
the profession of examining eyes, diagnosing defects in eyesight, and prescribing corrective lenses or exercises. |
| opulence |
the condition of being opulent. [2 definitions] |
| opulent |
having or displaying wealth and luxury. [2 definitions] |
| opus |
a work of fine or literary art, esp. a musical composition numbered to indicate its chronological place in the composer's works. |
| -or1 |
a variant of -er1. |
| -or2 |
activity; quality; condition; characteristic. |
| OR1 |
abbreviation of "Oregon," a northwestern U.S. state on the Pacific coast between Washington and California. |
| OR2 |
abbreviation of "operating room." |
| or |
used to indicate alternatives. [5 definitions] |
| oracle |
in ancient Greece, a shrine, priest, or priestess dedicated to a god and often consulted for prophecies or advice. [3 definitions] |
| oracular |
of, like, pertaining to, or having the nature of an oracle; prophetic; wise; mysterious. [3 definitions] |
| oral |
spoken, as opposed to written; accomplished by speaking. [3 definitions] |
| oral history |
historical data, often tape-recorded, that comprises firsthand oral accounts and recollections relating to historical events or traditions. [2 definitions] |