ووجهه أي وجه التشبيه ما يشتركان فيه
The aspect of resemblance is the meaning shared by the two compared terms.
Classifying the two terms tells us what things are compared. To complete the account, we must also ask in what respect they resemble each other. Zayd and a lion are both sensible beings, but this does not attribute every leonine trait to Zayd.
If courage is intended in “Zayd resembles a lion,” then courage is the wajh al-shabah. Redness can likewise be the aspect linking cheek and rose. This prepares the separate, more detailed classification of shared aspects.