Answer: INFINITESIMAL

AnswerCrossword Clue
INFINITESIMALNearly O
INFINITESIMALStart of the commentary
INFINITESIMALVery, very small
INFINITESIMALStart of a sizable observation
infinitesimalExtremely small
infinitesimaltaking on values arbitrarily close to but greater than zero / an infinitesimal number
infinitesimalindefinitely or exceedingly small; minute.