Plain English Meaning

Liquid inside the airplane's hydraulic system that has been squeezed to high pressure by a pump, so it can push parts like the landing gear up or down when the pilot selects a position.

Full Definition

Hydraulic fluid that has been forced under high pressure by a pump so that it can transmit force through hydraulic lines to operate aircraft components such as the landing gear, brakes, and flaps.

Context Anchor

Seen in landing gear system descriptions, especially when explaining how retractable landing gear extends, retracts, and locks.

Derivation

Hydraulic' comes from the Greek 'hydor' meaning , because early used water to transmit force. 'Pressurized' simply means raised to a higher than the surrounding . Together they a (today usually a oil, not water) that has been pumped up to high pressure so it can do mechanical .