Thanks for the replies. The person I am investigating is an Alexander
McGilichallum Munro who is listed in 1745 in Milntown (parish of Kilmuir Easter) on page 120 of David Dobson's book "Scottish Highlanders on the Eve of the Great Migration 1725 - 1775: The Northern Highlands" (
https://books.google.co.uk/books?id=UCfdGz0qv1kC&pg=PA120&lpg=PA120&dq=Munro,+Alexander+McGilichallum&source=bl&ots=2q0O2SZZpG&sig=XzvzlJ2giyYeF4U7GCJ_2QHGiNo&hl=en&sa=X&ved=0ahUKEwjo1d-32r3SAhXoBsAKHTtWDS8Q6AEIIjAB#v=onepage&q=Munro%2C%20Alexander%20McGilichallum&f=false)
There are two other Munros in different parishes in the same year with same alias and also someone with the surname Ross, again in a different parish with the same alias all in the same year of 1745. I am just wondering if this alias is more of a descriptive nickname rather than a description of lineage.
So far I have found and been given the following interpretations:
son of Gilbert son of Callum
son of the servant of Callum
son of Malcom
son of the youthful Colin
son of Gil/Gilbert, grandson of Malcolm
son of Gil/Archibald (Gilleasbaig being Archibald), grandson of Malcolm
McGilli/Gille etc does seem to commonly be son of the servant. For example Clan MacMillan: MacGillemhaoil which means "son of the tonsured servant".
Although if I have the lineage correct, the above mentioned Alexander McGilichallum Munro's brother, David Munro, had a grandson named Gilbert Munro, who could have been named after his great-grandfather/his father's grandfather Gilbert which is where the alias could have come from.
There are actually four with this name in the above mentioned book, although some are spelt with a double l:
Munro, Alexander McGilichallum in Milntown, soldier of George Munro of Culcairn's Independent Company, 1745. (parish of Kilmuir Easter, Ross-shire).
Munro, William McGilichallum in Balcony, soldier of George Munro of Culcairn's Independent Company, 1745. (parish of Kiltearn, Ross-shire).
Ross, John McGillichallum in Newtown, soldier of George Munro of Culcairn's Independent Company, 1745. (parish of Alness, Ross-shire).
Munro, George McGillichallum in Foulis, soldier of George Munro of Culcairn's Independent Company, 1745. (parish of Kiltearn, Ross-shire).
MacGillichallum, John in Langwell, Applecross, Wester Ross, 1718