linchpin /linchˈ or linshˈpin/

1. A pin used to keep a wheel on its axle
2. A person or thing essential to a plan, organization, etc (figurative)

• unextinct
• unextinguishable
• unextinguishably
• unextinguished
• unextreme
• uneyed
• unfabled
• unfact
• unfacts
• unfadable
• unfaded
• unfading
• unfadingly
• unfadingness
• unfadingnesses
• unfailing
• unfailingly
• unfair
• unfaired
• unfairer
• unfairest
• unfairing
• unfairly
• unfairness
• unfairnesses