na-adjective, noun which may take the genitive case particle 'no'
Describes something with substantial thickness, especially meat, flesh, or material that feels plump and substantial.
This steak is thick and juicy.
肉厚の葉っぱが特徴の植物です。
It's a plant characterized by its thick, fleshy leaves.
Compound of 肉 (niku, 'meat, flesh') and 厚 (atsu, 'thick'). The reading にくあつ is a straightforward combination of the on'yomi of each kanji.