1. Anxious or nervous to an excessive degree

See also: insecure

• hydrogen cyanide
• hydrogen fluoride
• hydrogen iodide
• hydrogen ion
• hydrogen ion concentration
• hydrogen peroxide
• hydrogen sulfide
• hydrogen sulphide
• hydrogen-bomb
• hydrogenate
• hydrogenation
• hydrogenise
• hydrogenize
• hydrogenous
• hydrographer
• hydrographic
• hydrographical
• hydrography
• hydroid
• hydroiodic acid
• hydrokinetic
• hydrokinetics
• hydrolise
• hydrolith
• hydrolize