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)

• polyphase
• polyphasic
• Polyphemian
• Polyphemic
• Polyphemus
• polyphenol
• polyphiloprogenitive
• polyphloesboean
• polyphloisbic
• polyphon
• polyphone
• polyphones
• polyphonic
• polyphonies
• polyphonist
• polyphonists
• polyphons
• polyphony
• polyphyletic
• polyphyllous
• polyphyodont
• polypi
• polypide
• polypides
• polypidom