Yoni Kootaयोनि
An Ashtakoot factor worth a maximum 4 points — assigns each of the 27 Nakshatras a symbolic animal (14 animals total: Horse, Elephant, Sheep, Serpent, Dog, Cat, Rat, Cow, Buffalo, Tiger, Deer, Monkey, Mongoose, Lion) and checks how compatible the couple's animal pairing is, classically read as an indicator of physical/sexual compatibility.
Certain animal pairs are classically considered natural enemies (e.g. cat and rat, or dog and deer) and would score poorly here even if other factors are strong — this is one of the more concrete, easy-to-visualize Ashtakoot factors.
Each birth Nakshatra maps to one of 14 Yoni animals via a fixed classical table; the groom's and bride's animals are compared against a friendship/enmity grid between all animal pairs, scored out of 4.