Two smiling first graders came to our door the other day. "Is clap an onomatopoeia?" they asked. "Hmm. Let me do some research," I told them. "I'll come to your room soon." The library books were all checked out. No website seemed completely credible...though some did indicate clap was an onomatopoeia. I clapped a few times in our office. It definitely is an onomatopoeia. They clapped when I came with the verdict.