姿势 (zīshì) refers to the physical posture or position of the body, especially how you hold it while standing, sitting, or moving. It is the most concrete and everyday word for 'posture' — unlike 姿态 (zītài), which can also mean a figurative 'attitude' or 'stance', and unlike 架势 (jiàshi), which implies a showy or aggressive stance. 体态 (tǐtài) focuses more on overall body shape and deportment, while 神态 (shéntài) is about facial expression.