Also called al·pha-naph·thyl group [al, -f, uh, -, naf, -thil groop, ‐-, nap, -thil], the univalent group C 1 0 H 7 –, having a replaceable hydrogen atom in the first, or alpha, position; 1-naphthyl group.

Also called be·ta-naph·thyl group [bey, -t, uh, -, naf, -th, uh, l groop, ‐-, nap, -thil], the univalent group C 1 0 H 7 –, having a replaceable hydrogen atom in the second, or beta, position; 2-naphthyl group.