Exceptionally large breasts. Customarily spoken as a compliment and in awe in description of a woman only to one's buddies, not to the woman's face - unless you, and she, are completely ghetto.
1) Defined as the reciprocal of infinity (1/infinity), if you say that pico and nano are "next to nothing", then infinitesimal has his cock up nothing's arse.
2) Just really, REALLY fucking small.
1) The reciprocal graph's distance from its asymptote gets infinitesimal, but they never meet.
2) The amount of homework I've done this evening lolololol