The reason why the Hijri months are called by their well-known names

Praise
be to Allah

Before Islam,
the Arabs used different names for the lunar months that were known at that
time, until those names changed and became standardised throughout Arabia,
and took their final forms at the end of the fifth century CE, during the
era of Kilaab, who was the great-great-great-great-great-grandfather of the
Prophet (blessings and peace of Allah be upon him).

The naming of
these lunar months with the names that are known today is based on certain
reasons and meanings from which the names of the months were derived, as was
mentioned by the scholars. Al-Haafiz Ibn Katheer (may Allah have mercy on
him) said:

Shaykh ‘Alam ad-Deen
as-Sakhaawi stated in a book that he compiled, entitled al-Mashhoor fi
Asma’ al-Ayyaam wa’sh-Shuhoor, that Muharram is so called because it is
a sacred (muharram) month. I think that it was so called to affirm its
sanctity, because the Arabs used to change it, making it not sacred one year
and making it sacred another year. He said: The plural form of Muharram is
Muharramaat or Mahaarim or Mahaareem.

Safar is so
called because their houses would be devoid of them when they went out to
fight or to travel, and it would be said “safira al-makaan (the place has
become empty)” when people left. The plural form of Safar is Asfaar.

Rabee‘ al-Awwal
is so called because they did not travel during that month (the word irtibaa‘,
derived from the same root, means “not travelling”). The plural form is
Arbi‘aa’, like the word naseeb (pl. ansibaa’), or Arbu‘ah like the word
ragheef (pl. arghufah). The same may be said concerning Rabee‘ al-Aakhir as
was said concerning Rabee‘ al-Awwal.

Jumaada is so
called because water froze during that month (jumood means freezing).

And he said: In
their calculations, the months did not rotate through the seasons, although
there is some doubt concerning that, because their months were connected to
lunar cycle, so they would inevitably rotate through the seasons. Perhaps
they called Jumaada by this name the first time, when water froze because of
the cold. The plural form of Jumaada is Jumaadiyyaat, like the word hubaara
(pl. hubaariyyaat). The word may be either masculine or feminine, so one may
say Jumaada al-Oola or al-Awwal, and Jumaada al-Aakhir or al-Aakhirah.

The name of
Rajab comes from the word tarjeeb, which means veneration. The plural form
is Arjaab or Rijaab or Rajabaat.

The name of
Sha‘baan comes from the word tasha‘‘ub (scattering), as the tribes would
scatter and disperse to raid others. The plural form is Sha‘aabeen or
Sha‘baanaat.

The name of
Ramadan comes from the word ramda’, which refers to intense heat. Another
word from the same root is used to refer to the thirst of camels when they
become thirsty. The plural form is Ramadaanaat or Ramaadeen or Armidah.

The name of
Shawwaal comes from a word referring to camels raising their tails for the
purpose of copulation. The plural form is Shawaawil or Shawaaweel or
Shawwaalaat.

The month of
Dhu’l-Qa‘dah – or, in my view, Dhu’l-Qi‘dah – is derived from the word
qu‘ood (rest), as during this month they would rest from fighting and
travelling. The plural form is Dhawaat al-Qa‘dah.

Dhu’l-Hijjah –
or, in my view, Dhu’l-Hajjah – is so called because they performed Hajj
during this month. The plural form is Dhawaat al-Hijjah.

End quote from
Tafseer Ibn Katheer (4/128-129)

See also: al-Mufassal
fi Tareekh al-‘Arab qabl al-Islam by the historian Jawaad ‘Ali (16/91ff)

There is nothing
wrong with mentioning the names of the months, explaining their meanings and
the sources from which they were derived, and the reasons why they are so
called, as explained by the historians and linguists, especially if there is
an educational purpose behind that, even though the origin may have been
forgotten and no longer has anything to do with the names of the months,
because they rotate through the seasons, as is well known, and therefore the
meaning has nothing to do with the well-known shar‘i rulings on the months.

For more
information, please see the answer to question no.
170242

And Allah knows
best.