ac ‧ cre ‧ tion /əˈkriːʃ ə n/ BrE AmE noun [uncountable and countable] formal
[ Date: 1600-1700 ; Language: Latin ; Origin: accretio , from accrescere , from ad- 'to' + crescere 'to grow' ]
1 . a layer of a substance which slowly forms on something
2 . a gradual process by which new things are added and something gradually changes or gets bigger