parahydrogen UK /ˌpæɹəˈhaɪdɹəd͡ʒ(ə)n/US /ˌpɛɹəˈhaɪdɹəd͡ʒ(ə)n/ noun1 •The form of the hydrogen molecule (H₂) in which the two nuclei have antiparallel spin; about 25% of hydrogen at room temperature. formsparahydrogens
