:: Meaning of some Common Islamic Terms in Arabic ::

Allāh - The Name of the one God we Worship. - Please make sure that you always write/type the Name of Allāh with a capital 'A'.

Allāhu Akbar = "Allāh is the Greatest"

Alhamdulillah = "All praise is due to Allāh"

Ameen = "O Allāh, accept our invocation"

Astaghfirullah = "I seek forgiveness from Allāh"

Audhubillah = "I seek refuge in Allāh"

Bismillah = "In the name of Allāh"

Insha'Allāh = "If Allāh wills"

FiAmanillah = "May Allāh protect you"

JazakAllahu Khayran = "May Allāh reward you for the good"

Masha'Allāh = "Allāh has willed it"

Subhan'Allāh = "Glory be to Allāh"

(plural reply to JazakAllahu khayran which means "and you all" - [i.e. May Allah reward you all too]
and JazakumAllahu khayran for all the encouraging comments!
 
BarakAllahu Fik = "May the blessings of Allah be upon you."
TabarakAllah = "Blessed is Allah"
 
The reason for using capital 'A' when writing/typing the Name of Allah is first and foremost due to
the respect that Allah (Subhanahu Wa Ta'ala) deserves. Then as per English grammar rules, a Proper Noun [i.e. nouns that refer to specific entities] must be capitalized.
 
The Arabic word for great is 'kabir' and for greater/greatest is 'akbar'. Following is just one example each for kabir/akbar from the Qur'an:
AKBAR:
Transliteration: "FayuAAaththibuhu Allahu alAAathaba alAKBARa" (The Qur'an 88:24)
Translation: "Then Allâh will punish him with the GREATEST punishment." (The Qur'an 88:24)
 
KABIR:
Transliteration: "Wakathalika jaAAalna fee kulli qaryatin aKABIRa mujrimeeha liyamkuroo feeha wama yamkuroona illa bianfusihim wama yashAAuroona" (The Qur'an 6.123)
Translation: "And thus We have set up in every town GREAT ones of its wicked people to plot therein. But they plot not except against their ownselves, and they perceive (it) not." (The Qur'an 6.123)"