Denshi Jisho — Online Japanese dictionary

姿勢 しせい attitude; posture; stance; approach; carriage (of the body)
Common word, Noun 
姿勢反射 しせいはんしゃ postural reflex
Noun 
姿勢を正す しせいをただす to straighten oneself
Expression, Godan verb with su ending 

You can also

Look up kanji details for 姿勢.

Try a Yahoo Jisho search for 姿勢 .
Try a Goo Jisho search for 姿勢 .
Try a Google search for 姿勢 .