altitude |
in geometry, the perpendicular distance from a vertex to its base or opposite surface. [1/4 definitions] |

birefringence |
the splitting of a light wave into two perpendicular waves that have different speeds, as in some crystals. |

Cartesian coordinates |
a pair of coordinates for locating a point on a plane by its distances from two intersecting, usu. perpendicular lines. [2 definitions] |

dragonfly |
any of a large group of brightly colored insects with four long, veined, translucent wings usu. held perpendicular to a long, narrow body. |

equatorial |
a telescope mounted on two axes, one parallel to and one perpendicular to the earth's axis of rotation. [1/3 definitions] |

octant |
any of the eight parts into which three-dimensional space is divided by three mutually perpendicular planes. [1/4 definitions] |

orthorhombic |
of or denoting a pattern of crystallization embodying three mutually perpendicular axes of different lengths. |

perpendicular |
a perpendicular line or plane. [2/7 definitions] |

plumb |
in a perpendicular or vertical line. [1/10 definitions] |

precession |
the complex motion of a rotating body, such as a spinning top, when subjected to a disturbing force or torque that tends to move the axis of rotation in a direction perpendicular to the direction of the force, causing it generally to describe a cone. [1/3 definitions] |

rake^{1} |
a tool consisting of a long handle and a row of tines extending perpendicular to it, used for gathering up debris or cultivating the ground. [1/12 definitions] |

rake^{3} |
the angle at which a cutting or inscribing tool inclines from the perpendicular when applied to a surface. [1/4 definitions] |

right angle |
an angle formed by the meeting of two perpendicular lines and measuring ninety degrees. |

square |
forming a right angle; perpendicular. [1/24 definitions] |

up-and-down |
vertical or perpendicular. [1/3 definitions] |

vertical |
perpendicular to level ground; extending at right angles to the horizon; upright. [1/4 definitions] |

vertical circle |
an imaginary circle on the celestial sphere that passes through the zenith and nadir and is thus perpendicular to the horizon. |