Islamic Calendar

General

The Hijri calendar (Arabic: ٱلتَّقْوِيم ٱلْهِجْرِيّ‎ at-taqwīm al-hijrīy), also known as the Lunar Hijri calendar and (in English) as the IslamicMuslim or Arabic calendar, is a lunar calendar consisting of 12 lunar months in a year of 354 or 355 days. It is used to determine the proper days of Islamic holidays and rituals, such as Ramadan, the annual period of fasting and the proper time for Hajj. 

1al-Muḥarramٱلْمُحَرَّم‎forbiddenA sacred month, so-called because battle and all kinds of fighting are forbidden (ḥarām) during this month. Muharram includes Ashura, the tenth day.
2Ṣafarصَفَر‎voidSupposedly named this because pre-Islamic Arab houses were empty this time of year while their occupants gathered food.
3Rabīʿ al-ʾAwwalرَبِيع ٱلْأَوَّل‎the first springAlso means to graze, because cattle were grazed during this month. Also, it is a very holy month of celebration for many Muslims, as it was the month the Prophet Muhammad was born and was the same month as his death.
4Rabīʿ ath-Thānī
or
Rabīʿ al-ʾĀkhir
رَبِيع ٱلثَّانِي‎
or
رَبِيع ٱلْآخِر‎
the second spring, the last spring
5Jumadā al-ʾŪlāجُمَادَىٰ ٱلْأُولَىٰ‎the first of parched landOften considered the pre-Islamic summer. Jumādā may also be related to a verb meaning “to freeze” and another account relates that water would freeze during this time of year.
6Jumādā ath-Thāniyah
or
Jumādā al-ʾĀkhirah
جُمَادَىٰ ٱلثَّانِيَة‎
or
جُمَادَىٰ ٱلْآخِرَة‎
the second of parched land, the last of parched land
7Rajabرَجَب‎respect, honourThis is the second sacred month in which fighting is forbidden. Rajab may also be related to a verb meaning “to remove”, so called because pre-Islamic Arabs would remove the heads of their spears and refrain from fighting.
8Shaʿbānشَعْبَان‎scatteredMarked the time of year when Arab tribes dispersed to find water. Sha‘bān may also be related to a verb meaning “to be in between two things”. Another account relates that it was called thus because the month lies between Rajab and Ramadan.
9Ramaḍānرَمَضَان‎burning heatBurning is related to fasting as with an empty stomach one’s worldly desire will burn. Supposedly so-called because of high temperatures caused by the excessive heat of the sun. Ramaḍān is the most venerated month of the Hijri calendar. During this time, Muslims must fast from pre-dawn until sunset and should give charity to the poor and needy.
10Shawwālشَوَّال‎raisedFemale camels would normally be in calf at this time of year and raise their tails. At the first day of this month, the Eid al-Fitr, “Festival of Breaking the Fast” begins, marking the end of fasting and the end of Ramadhan.
11Ḏū al-Qaʿdahذُو ٱلْقَعْدَة‎the one of truce/sittingThis is a holy month during which war is banned. People are allowed to defend themselves if attacked.
12Ḏū al-Ḥijjahذُو ٱلْحِجَّة‎the one of pilgrimageDuring this month Muslim pilgrims from all around the world congregate at Mecca to visit the Kaaba. The Hajj is performed on the eighth, ninth and tenth of this month. Day of Arafah takes place on the ninth of the month. Eid al-Adha, the “Festival of the Sacrifice”, begins on the tenth day and ends on the sunset of the twelfth, and this is the fourth holy month during which war is banned.