[{"Bold_text": "adjective", "List Items": ["exceedingly small; minute :Capillaries, the infinitesimal vessels in our circulatory system, are small enough that red blood cells must flow through them single-file.", "Mathematics.immeasurably small; less than an assignable quantity:An infinitesimal number is never zero, but it comes pretty close.of, relating to, or involving variables having zero as a limit:infinitesimal calculus.", "immeasurably small; less than an assignable quantity:An infinitesimal number is never zero, but it comes pretty close.", "of, relating to, or involving variables having zero as a limit:infinitesimal calculus."]}, {"Bold_text": "noun", "List Items": ["an infinitesimal quantity.", "Mathematics.a variable having zero as a limit."]}, {"Bold_text": "Adjective", "List Items": null}, {"Bold_text": "Noun", "List Items": null}]