a recognized sequence of moves at the beginning of a game of chess | the outer boundary of an artifact or a material layer constituting or resembling such a boundary |
the act of opening something | a device that provides reactive force when in motion relative to the surrounding air; can lift or control a plane in flight |
becoming open or being made open | a superficial aspect as opposed to the real nature of something |
the first of a series of actions | information that has become public |
a vacant or unobstructed space that is man-made | the extended two-dimensional outer boundary of a three-dimensional object |
an entrance equipped with a hatch; especially a passageway between decks of a ship | the outermost level of the land or sea |
an aperture or hole that opens into a bodily cavity | |
a possible alternative | |
the initial part of the introduction | |
the first performance (as of a theatrical production) | |
a ceremony accompanying the start of some enterprise | |
an open or empty space in or between things | |
opportunity especially for employment or promotion | |