Principal-plane
noun, Optics.
1.
a plane that is perpendicular to the axis of a lens, mirror, or other optical system and at which rays diverging from a focal point are deviated parallel to the axis or at which rays parallel to the axis are deviated to converge to a focal point.
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noun 1. a diagonal member of a roof principal, usually forming part of a truss and supporting the purlins on which the common rafters rest.
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noun, Mathematics. 1. composition series. composition series noun, Mathematics. 1. a normal series of subgroups in which no additional subgroups can be inserted.
- Principalship
adjective 1. first or highest in rank, importance, value, etc.; chief; foremost. 2. of, of the nature of, or constituting principal or capital: a principal investment. 3. Geometry. (of an axis of a conic) passing through the foci. noun 4. a chief or head. 5. the head or director of a school or, especially in […]