What is Makrooh?

On some things where the Quran and Sunnah are silent,  and it becomes evident that these things are impure and unsuitable for the believers in light of the guidance of the Quran and Sunnah;  the scholars have termed such things Makrooh or disliked.   Example being cigarettes,  etc.

Everything that is declared Haraam by Allah and His Messenger (saws) are also disliked,  and thus every Haraam thing will also be considered Makrooh;   but not all makrooh things will necessarily be considered Haraam.

Sahih Al-Bukhari Hadith 3.267         Narrated by An Numan bin Bashir

The Prophet (saws) said "Both, halaal and haraam things are obvious, and in between them are (suspicious) doubtful matters.  So whoever forsakes those doubtful things lest he may commit a sin, will definitely avoid what is clearly illegal; and whoever indulges in these (suspicious) doubtful things bravely, is likely to commit what is clearly illegal.   Sins are Allah's Hima (i.e. private pasture) and whoever pastures (his sheep) near it, is likely to get in it at any moment."

What Is Sharia?

Sharia or "path" in Arabic is the Islamic Law  that guides all aspects of Muslim life, including daily routines, familial and religious obligations, and financial dealings. It is derived primarily from the Quran and the Sunna—the sayings, practices, and teachings of the Prophet Mohammed. Precedents and analogy applied by Muslim scholars are used to address new issues. The consensus of the Muslim community also plays a role in defining this theological manual.