Origin: Latin suffix -able
Unreliable has 5 different meanings across 1 category:
not worthy of reliance or trust
"in the early 1950s computers were large and expensive and unreliable"
"an undependable assistant"
dangerously unstable and unpredictable
"treacherous winding roads"
"an unreliable trestle"
lacking a sense of responsibility
"The new manager is completely unreliable because he never shows up to meetings or finishes his assigned tasks on time."
Not reliable.
"The car broke down again, proving it is completely unreliable."