underweight
adjective
• below a weight considered normal or desirable.
• "he was thirty pounds underweight"
• having less investment in a particular area than is normal or desirable.
• "the company is still underweight in Japan"
underweight
verb
• apply too little weight to.
• "we feared the hot-air balloon had been underweighted"
underweight
noun
• insufficient weight.
• "thinness and underweight may be a physical quality that you and I share"