This is the 950th most frequent Hindi word.
सद
The Hindi word "सद" means "eternal," "good," or "virtuous."
In this sentence, 'सद' functions as a prefix indicating good or noble qualities associated with 'विचार' (thoughts).
सद विचार हमेशा उन्नति की ओर ले जाते हैं।
Noble thoughts always lead to progress.
In this case, 'सद्भावना' combines 'सद' with 'भावना' (feelings), conveying the idea of positive or good feelings.
सद्भावना ही समाज में शांति लाती है।
Goodwill brings peace to society.
Here, 'सदाचारी' denotes someone who adheres to moral or ethical conduct, with 'सद' imbuing a positive moral quality.