In Islamic terminology, something which is makruh (Arabic: مكروه, transliterated: makrooh or makrūh) is a disliked or offensive act (literally "detestable" or "abominable"), one of the five categories (or "Ahkam pentad") in Islamic law -- wajib/fard (obligatory), Mustahabb/mandub (recommended), halal/mubah (permitted), makruh (disapproved), haram (forbidden). Though it is not haram (forbidden) or subject to punishment, a person who abstains from this act will be rewarded.Muslims are encouraged to avoid such actions when or as possible. This is one of the degrees of approval (ahkam) in Islamic law.
Examples of something considered Makruh are the use of a great amount of water for the pre-prayerablutions (ritual washings) known as the wudu and ghusl, the consumption of garlic before attending the mosque or socializing with others, or divorce.
An example of a food which is considered "Makruh" for Muslims of the Hanafi Madh'hab is prawns (but only for HanafiMadh'hab Muslim). There are, however, shared attitudes within the Hanafi school of whether shrimp are considered water game and are thereby halal. Hanafis believe that you should refrain from it and eat something else if possible. 
Other examples of Makrooh acts in Islam are: Smoking, talking while taking ablution/wudu for prayer, slaughtering an animal for food while other animals of its kind can see, etc