Chem.
1. Also called alpha-naphthyl group, alpha-naphthyl radical . the univalent group C 10 H 7 -, having a replaceable hydrogen atom in the first, or alpha, position; 1-naphthyl group.
2. Also called beta-naphthyl group, beta-naphthyl radical . the univalent group C 10 H 7 -, having a replaceable hydrogen atom in the second, or beta, position; 2-naphthyl group. Also called naphthyl radical .