1. moving the arms in large circular motions like the blades of a windmill
Usage: present participle of windmill

1. the action of moving the arms or limbs in large circular motions
Usage: gerund form

Examples

• The swimmer was windmilling her arms to stay afloat.
• He started windmilling his arms wildly when he lost his balance.
• The coach demonstrated proper windmilling technique for the backstroke.
• Her windmilling motion helped her regain stability on the ice.
• The child was windmilling his arms excitedly as he ran toward the playground.
• The pitcher’s windmilling delivery confused the batter.