Phonetic pet form of Gertrude, from Germanic 'ger' (spear) and 'thrud' (strength).
Girthie is a phonetic pet form of Gertrude, the Germanic name built from ger, meaning spear, and thrud, meaning strength. That means the name’s underlying history is martial and forceful, even though the nickname form sounds soft and affectionate.
Girthie has the texture of an older diminutive, likely suited to family use or informal speech rather than official formality. It sounds quaint and warmly old-fashioned, with the kind of intimate charm that nickname names often develop. The contrast between its sweet surface and strong roots is part of what makes it interesting.