The islamic calendar is purely lunar and consists of 12 months. While it is a divine order by Allah to observe such calendar system, the names of the months in the islamic calendar was not pre-defined by Allah or the Messenger pbuh. The months inherited the names from the time of Jahiliya (pre-islamic periods), the names that were traditionally used at that time.
The meaning of islamic months
1. Muharram: is named so because the Arabs used to prohibit fighting during it.
2. Safar: is named so because the Arabs used to leave their homes during that month as they used to set out to fight their enemies. It is also said that they used to leave their homes to escape summer heat.
3. Rabi` al-Awwal: is named so because it usually coincides with the spring time.
4. Rabi` al-Akhar: is named so because it usually coincides with the winter time.
5. Jumada al-Ula: The Arabs named it so because water gets frozen at winter time, and that coincides with the time of Jumada al-Ula.
6. Jumada al-Ukhra: is named so because it coincides with winter time.
7. Rajab: is derived from the Arabic word rajab which means to sanctify something. The Arabs used to sanctify the month of Rajab by putting a halt to fighting during that month.
8. Sha`ban: The Arabic word Sha`ban is derived from the word tash`aba, which means to go in different directions. It is said that Sha`ban takes such a name because the Arabs used to go in different directions fighting their enemies.
9. Ramadan: The word Ramadan is derived from Ar-ramda which refers to extreme heat. Ramadan time used to coincide with that extreme climate of heat in the Arab Peninsula, and that is why it is called Ramadan.
10. Shawwal: The name Shawwal is derived from the Arabic word tashawwala, which refers to the scarcity in she-camels milk.
11. Dhul-Qi`dah: refers to the Arabs’ decline to go out fighting their enemies as the early Arabs used to call it a sacred month.
12. Dhul-Hijjah: is named so because the Arabs used to perform Hajj during that month.
Hope that gives us more understanding and love to our islamic calendar system.