aa

Everyday

1. (science) Aa (from Hawaiian «ʻaʻā») is a kind of lava that cools into rough, sharp, jagged lumps. tree →
2. (abbreviation) AA is a battery size: a small cylinder battery used in remote controls and toys («AA batteries»). tree →
3. (UK) The AA is the Automobile Association, which helps drivers whose cars break down. tree →
4. (abbreviation) AA also means Alcoholics Anonymous, a group that helps people stop drinking alcohol. tree →

In the lessons

In science lessons about volcanoes, aa lava is contrasted with pahoehoe, which is smooth and ropy. In everyday life «AA» is most often a battery size: AA is bigger than AAA. On road signs in the UK, yellow AA signs show detours. Say «ah-ah» for the lava.

Examples

• Aa lava is rough and sharp, so you must never walk on it. tree →
• The remote needs two AA batteries. tree →
• AAA batteries are thinner than AA ones. tree →
• Our car broke down, so Dad called the AA. tree →
• On Hawaii we saw fields of black aa lava. tree →
• The scientist explained the difference between aa and pahoehoe. tree →

Note

The lava word is Hawaiian and sounds like «ah-ah». Capital «AA» is an abbreviation: for batteries, the Automobile Association, or Alcoholics Anonymous — which one depends on context. Not a normal English word on its own.