qepHom 2015: "vein" is 'aD. In general usage, this means either a vein or an artery, so a better translation might be "blood vessel." In medical usage, however, doctors and so on make a distinction between mej'aD "artery" and paw'aD "vein." Maltz said that he thought that earlier these were mejmeH 'aD and pawmeH 'aD, but over time they were shortened.