Glides

Glide is a term used across several disciplines to describe a smooth, continuous motion with minimal propulsion. In flight, a glide refers to unpowered movement through the air, sustained by lift and gravity. On land or water, gliding describes motion with little friction, such as skating on ice or sliding over a polished surface.

In aviation, gliding describes flight with no sustained engine thrust. Gliders, or sailplanes, rely on aerodynamic lift, gravity, and atmospheric currents to travel forward while descending gradually. Performance is often expressed as a glide ratio, the horizontal distance traveled per unit of altitude lost, with higher ratios indicating greater efficiency.

Natural gliders include many bird species, such as albatrosses and eagles, which exploit air currents to extend range and conserve energy. Wing shape, aspect ratio, and feather arrangement enable smooth, continuous descent and long-distance travel without flapping.

In linguistics, a glide (or semivowel) is a sound that lies between a vowel and a consonant, as in the English sounds of "y" in yes or "w" in wet. Glides function as transitions between vowels in syllables.

Glide concepts also appear in sports and engineering as a metaphor for smooth movement and energy efficiency, including activities like skating on a smooth surface or the study of gliding flight to improve unpowered aircraft design.