Definition
A chemical compound formed by combining a metal or other positive ion with the hydroxyl group (OH). Hydroxides are typically alkaline (basic) and are commonly found in cleaning agents, batteries, and industrial chemicals used in aircraft maintenance.
Plain English
A chemical made up of a metal joined with an oxygen-and-hydrogen pair (OH). Most hydroxides are caustic — they can burn skin and corrode materials.
Context Anchor
Seen in aircraft maintenance discussions involving batteries, chemical leaks, corrosion control, and cleaning compounds.
Derivation
From 'hydro-' (Greek hydor, water) and 'oxide' (a compound of oxygen). The name reflects that a hydroxide can be thought of as water (H₂O) with one hydrogen replaced by another element — leaving the OH group attached.
Why Pilots Care
Sodium hydroxide and potassium hydroxide are found in some aircraft batteries (nickel-cadmium) and certain cleaners. They are caustic and can cause chemical burns or damage aluminum aircraft structures if spilled and not neutralized properly.
Grounding Statement
If you see hydroxide mentioned near an aircraft battery or spill, think “strong chemical that can burn or corrode,” not “ordinary liquid.”
Intuition Check
Do not assume “hydroxide” means water or something harmless because it starts with “hydro.” Here it means a specific oxygen-hydrogen chemical group that often makes a substance strongly alkaline and corrosive.
Example Sentence 1
The maintenance technician wore protective gloves when servicing the nickel-cadmium battery because the potassium hydroxide electrolyte is highly caustic.
Example Sentence 2
Maintenance staff check the condition of the hydroxide solution during battery servicing.