Terminology means ‘a set of words used in a specially understood or defined sense’. From the standpoint of an international journal welcoming English language material from all over the world, it is apparent that widespread differences in meaning and uses of terminology exist in the field of developmental medicine. Differences in terminology matter, as Bax and Mac Keith commented, ‘First, foremost, surely, is how careful we must be in our language. If words are used... (that) confuse us they may in fact harm the patient’.