I have created a public synonym on a feature class (oracle sdo_geometry) and provided suitable grants to users to access and edit.
It is not visible when i logged using arc catalog.
Please help me.
Synonyms might be accessible from Query Layers (never tried it), but certainly not as an enterprise geodatabase feature class. The layer registration process is incompatible with "tables" that aren't really owned by users and don't exist when referenced by owner.
The Knowledge Base covers this:
36137 - Are Oracle public synonyms supported in ArcGIS for referencing a table?
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