Suffice - глагол в значении "быть достаточным". http://www.oxforddictionaries.com/ru/%D0%BE%D0%BF%D1%80%D0%B5%D0%B4%D0%B5%D0%BB%D0%B5%D0%BD%D0%B8%D0%B5/%D0%B0%D0%BD%D0%B3%D0%BB%D0%B8%D0%B9%D1%81%D0%BA%D0%B8%D0%B9/suffice?searchDictCode=all Sufficient - прилагательное - "достаточный". http://www.oxforddictionaries.com/ru/%D0%BE%D0%BF%D1%80%D0%B5%D0%B4%D0%B5%D0%BB%D0%B5%D0%BD%D0%B8%D0%B5/%D0%B0%D0%BD%D0%B3%D0%BB%D0%B8%D0%B9%D1%81%D0%BA%D0%B8%D0%B9/sufficient?searchDictCode=all Вообще советую пользоваться оксфордским или кэмбриджским англо-английскими словарями, чтобы увидеть разницу в подобных словах.

Jingyi is correct. You can use the verb "suffice" in a sentence such as this: "Ten kilos of meat will suffice for the party." However, the verb "suffice" is a formal word. In ordinary, colloquial speech, most people would say, "Ten kilos of meat will be be sufficient for the party," or "Ten kilos of meat will be enough for the party." Or you could use the adjectives sufficient or enough: "Ten kilos of meat will be sufficient/enough for the party."

suffice is a verb, sufficient is a adjective