1. Subject to or caused by an earthquake or earth vibration
   - seismic

See also: seism, unstable

• opt
• opt out
• optative
• optative mood
• Optez
• opthalmic
• optic
• optic axis
• optic chiasm
• optic chiasma
• optic cup
• optic disc
• optic disk
• optic nerve
• optic radiation
• optic tract
• optical
• optical aberration
• optical activity
• optical art
• optical bench
• optical character recognition
• optical condenser
• optical crown
• optical crown glass