tack-on

Translations
добавка
дополнение
приставка
надстройка
довесок
надбавка
Definitions
An additional thing attached or added to something else, especially after the main part has been completed.
An extra cost or charge added to a price or bill.
Something added as an afterthought and often not well integrated with the original whole.
Words
tack

noun
добавка
on

adverb
дополнительный