English – like all languages – has a predilection for ‘rules’, as grammatical patterns are often called. Generally the patterns are fairly straight-forward, though sometimes they become rather complex, perhaps with numerous exceptions or irregular features. To further obscure the picture, language patterns do not stay still, variations occurring in place and time. At first sight, English word-building elements – such as prefixes and suffixes – would appear to be fairly regular, presenting clear morphological patterns with few exceptions. But first appearances can be deceptive.