Clippings, or truncations, are shortened word forms. They are perfectly acceptable informally, but their suitability for formal English depends
on the rather subjective criterion of how well established they are.
The following, for example, should be spelt in full in formal English –
These are now formally acceptable and, in most circumstances, preferable to their full alternatives –
vet (veterinary surgeon)
while opinion might differ on these –
The practice of using apostrophes with clippings ('piano, lab') is obsolete.