ADELISA Fitz Richard de Clare (-[1125/35] or after). She is called Adelidem filiam Ricardi de…prosapia Gifardorum by Orderic Vitalis, who also records her marriage. Her identification as the daughter of Richard de Clare was first made by Round. Adelissa [mater Gauterii filii Gauterii Tirelli] donated property to the abbey of Saint-Martin de Pontoise by charter dated [1125/35] which states that the donation was made after the death of her son and the latter was buried at the abbey. The same charter also records a later donation by Gauterius Tirellus pater memorati Gauterii iuvenis witnessed by Ada uxore Hugonis Tirelli, Gauterius Tirelli et Hugonis filii eius. The 1130 Pipe Roll records Adeliz uxor Walti Tirelli in Essex in relation to eisde plac de La Wingeha. m GAUTHIER [II] Tirell, son of GODRICH & his wife Aremburgis --- (-Jerusalem after [1140]).[1]
Featured German connections: Adelisa is 24 degrees from Johann Wolfgang von Goethe, 33 degrees from Dietrich Bonhoeffer, 26 degrees from Lucas Cranach, 29 degrees from Stefanie Graf, 27 degrees from Wilhelm Grimm, 28 degrees from Fanny Hensel, 33 degrees from Theodor Heuss, 26 degrees from Alexander Mack, 43 degrees from Carl Miele, 24 degrees from Nathan Rothschild, 27 degrees from Hermann Friedrich Albert von Ihering and 25 degrees from Ferdinand von Zeppelin on our single family tree. Login to see how you relate to 33 million family members.
Living in that era, Adeliza would not have had a last name. She would have been known in relation to her father and, later, her husband. In Anglo-Norman, it might have been rendered something like "Adeliza la fille Richarde de Clare". Or in Latin, something like "Adeliza filia Ricardi de Clare". Such a description would be the most historically accurate way to describe her for the bio, but Wikitree needs a LNAB, even for people who never had one. Here, the choice of "Clare" seems reasonable and neatly avoids the issue of the feminine Fitz!
Even though "Fitz" means "son of", I've never seen the female equivalent "Fille" used as part of a last name for a daughter. Personally, I'm happy to use "Fitz" for a daughter, with the proviso that I recognise that the last name is an artificial construct to start with. I've seen genealogists such as Douglas Richardson do the same, which is probably where I've adopted the practice from.
But I might use "FitzRichard" rather than "FitzGilbert" as her father was named Richard. But there is also an argument for "FitzGilbert", to get around the clumsy use of "Fitz" for a female. By using "FitzGilbert", we would be saying that it was a hereditary surname from her grandfather, at a time when hereditary surnames did not exist, so this is also clumsy! For Wikitree, I would probably add both "FitzRichard" and "FitzGilbert" as Other Last Names, to help with searching.
These two G2G questions have contributions from leaders of the England/Euroaristo/Magna Carta projects. As you can see, there was no real consensus:
https://www.wikitree.com/g2g/724830 https://www.wikitree.com/g2g/1012448
The England Project doesn't have any particular policies on this, we treat each one on a case-by-case basis and use G2G if we're unsure.
Fitz by definition means SON of [typically illegitimate] in that era.
So, Adeliza can't be a Fitz anything.