同位素 (Tông-ūi-sò͘) (isotope) 是 (sī)1種 (chióng)化學 (hoà-ha̍k)元素 (goân-sò͘) (chemical element) 的 (ê)無 (bô)仝 (kāng)形式 (hêng-sek); 因 (in)原子核 (goân-chú-hu̍t) (atomic nucleus) 的原子番 (goân-chú-hoan) (atomic number) 相 (sio)siâng,這輛翻 (chit-liōng-hoan) (mass number) 無仝 (kâng); 徛 (khiā)講 (kóng)陽子 (iông-chú)平 (pêⁿ)這 (che)粒 (lia̍p),毋過 (m̄-koh)中子 (tiong-chú)無平坐 (chē)。
同位素本底 (pún-té)的意思 (ì-sù)是講佇 (tī)週期表 (chiu-kî-pió)占 (chiàm)共 (kāng)1位 (ūi)的元素。同位素佇科學 (kho-ha̍k)的號名法 (hō-miâ-hoat) (nomenclature) 是用 (ēng)元素的名字 (miâ-jī)街 (ke)1个 (ê)年二號 (liân-jī-hō),後壁 (aū-piah)閣 (koh)接 (chiap)質量翻 (chit-liōng-hoan)來 (lâi)表示 (piáu-sī),親像 (chhin-chhiūⁿ)講彼 (He)3 (helium-3),C-12 (carbon-12),C-14 (carbon-14),伊 (I)131 (iodine-131),U-238 (uranium-238)。佇化學符號 (hû-hō) (chemical symbol) 就 (tō)共 (kā)這輛翻囥 (khǹg)佇元素符號頭前 (thaû-chêng)頂懸 (téng-koân),像 (chhiūⁿ)講 3彼,12C,14C,131伊和 (hām) 238U。