'In tails' means dressed formally in full evening dress for men.

I believe you mean the word "entail". Like: "What does this entail?" A trip to America from Brazil entails applying for a visa.

I'm not sure what you mean but it would help if you include more details... "Tail" can mean a word for what Elephants and dogs and other animals have on their backside to get rid of insects who bite them or for animals like dogs and cats as a way of show expression etc. Here are some definitions of the word "tail" http://www.definitions.net/definition/tail If you meant entail (นำมาซึ่ง) , it is to involve something or to impose or to demand... "We shall entail" meaning we shall get involved / or we shall impose or we shall require (need) Hope that helps. For example: In order for you to graduate from university this entails a lot of study. (To be able to graduate in univeristy this "requires" a lot of studying) Anthony Perez has a good example too I will "entail" (include) many books in my studies in order to graduate from university. Hope that helps, feel free to ask us should you need more help :)