Deuterium and its compounds (including heavy water) in which the ratio of the number of deuterium atoms to normal hydrogen atoms exceeds 1 : 5000.
Deoitéiriam agus a chomhdhúile (lena n-áiritear uisce trom) inar mó ná 1:5000 an coibhneas idir uimhir na n-adamh deoitéiriam agus uimhil na n-adamh normalach hidrigine.