In this word. we have a root ie.. veter--that have lasted a long time and seem likely to continue. This itself gives an idea of the meaning.
World war II veterans. veter is a root which means for a long time
in + veter (water) + ate -> even in water (flood) a deeply rooted tree will stand still...
He had the habit of collecting information about different animals and he chose to study vet (veterinary) as his professional course.
invert + rate >>> yane jab koi shopkeeper ya koi bhaji wala rate bolata hai, tab womens ko AADAT(habitual) hoti hai bhaav karne ki
Inveterate = In + better + ate; He ated in good manner so he will lasting long.
These veteran smokers are inveterate smokers