People have a general tendency to be lazy, so they find whatever way they can to save time and energy. In the case of speaking English, they try to compress chunks of words as much as possible to minimize the effort required, and maximize the meanings expressed.

Some familiar examples would be ‘gonna’, ‘wanna’, and ‘gotta’. These three words are contracted forms of ‘going to’, ‘want to’ and ‘got to’ respectively. In all cases, the vowel in the preposition ‘to’ is weakened, and the whole preposition is glued and assimilated to the preceding verb.

These are only particular cases, because we cannot take a verb randomly and join it to ‘to’ at will. For instance, ‘wisha’ (wish to) and ‘likka’ (like to) will not do. We therefore say this operation is unproductive.

A lot of words have evolved this way. Some more transparent examples are ‘nevertheless’, ‘nonetheless’, and ‘notwithstanding’. Some other examples may be less easy to spot. ‘Albeit’, for instance, comes from the phrase ‘although be it’ in Middle English. And, believe it or not, the simple word ‘bye-bye’ is a word that has gone through a whole chain of changes. Obviously enough, ‘bye-bye’ is a replication of the word ‘bye’, which in turn is a shortened form of ‘goodbye’. What might be harder to guess is that ‘goodbye’ derives from the word ‘godbwye’, which ultimately can be traced back to the phrase ‘God be with ye’ in Middle English.

Another interesting one is ‘okay’, or ‘o.k.’ It derives from the initial letters of the phrase ‘oll korrect’, a deliberate misspelling of ‘all correct’.

Some other operations may be luckier and have become more productive. The suffix ‘-ful’, for example, was originally a contracted, or cliticized, form of ‘full’. It was used in its present sense as in the sentence “There is a cup full of water.” Gradually, the noun ‘cup’ and the adjective ‘full’ merged to form a new word ‘cupful’. This operation was later extended to form adjectives like ‘careful’ and ‘respectful’, and became further popularized afterwards.