Straight muscle; in human anatomy referring specifically to the muscle located at the back of the head.

In a broader sense, referring to something being straight or upright.

सही या सीधा

English Usage: He tried to maintain a rectus posture while walking.

Hindi Usage: वह चलने के दौरान सही मुद्रा बनाए रखने की कोशिश कर रहा था।

Correct or right, often used in moral contexts.

सही या उचित

English Usage: It is rectus to tell the truth.

Hindi Usage: सत्य कहना सही है।