speck

[1]	spot , pinpoint , dot , fleck , mote , speckle , mark , bit , particle , crumb , iota , jot (or tittle) , whit , atom , molecule , touch , hint , suggestion , suspicion , tinge , modicum , amount , grain , smidgen/smidgin
[2]	atom , molecule , particle , corpuscle , mote
[3]	touch , hint , tinge , mite , pinch , jot , soupcon