The word Yoni represents the reproductive organ of woman and as the name implies it ensures sexual compatibility and mutual love existence between the couple. Each Birth Star is associated with animal force that indicates compatibility between the bride and groom.

Out of these animal implications, cow and tiger, elephant and lion, horse and buffalo, dog and deer, rat and cat, snake and mongoose, goat and monkey are considered to be enemies to each other. When the Birth Stars fall under these categories, they are considered to be incompatible. However if the Birth Stars belong to the same Yoni, but are enemies to one another such as dog and cow can be a secondary option.