We do not currently know of any synonyms for fatha.
The noun fatha is defined as:
In Arabicscript, the vowel point for a, appearing as a diagonalline placed above a letter ( ـَ ) and designating a short a /a/. If the Arabic letters ا (أَلِف (ʾalif)) or ى (أَلِف مَقْصُورَة (ʾalif maqṣūra)) immediately follow, it indicates a long ā /aː/.