Oscitance is a rare word that means the act of yawning. However, if you're looking for synonyms to use in your writing, there are plenty of other options. Some possible choices include yawning, gaping, stretching, and panting. Additionally, you could try words like fatigue, drowsiness, sleepiness, or lethargy, which all evoke feelings of tiredness and laziness. If you want to convey a more positive or excited feeling, you could use words like enthusiasm, excitement, anticipation, or eagerness to describe someone's behavior. Ultimately, the word you choose will depend on the context and tone of your writing, so try a few different options to see what works best!