Particle, bit, mite, smidgen, whit, atom, iota, jot, tittle all mean a very small or insignificant piece or part.
Particle is used in reference not only to substances which are actually divisible but to such things as a quality, a state, or a condition which are only theoretically so because they are intangible or ideal; usually it implies an amount within the range of visual or mental perception.
Bit usually suggests a relatively minute or the least feasible amount, extent, or degree.
Mite may stress either diminutiveness in size or minuteness in amount.
Smidgen may replace bit or mite, but sometimes and especially in negative constructions it may go even farther in stressing minuteness or scarcity.
Whit is used chiefly in negative phrases in the sense of the least conceivable amount.
Atom (see also PARTICLE 2 ) implies an amount or a size beyond the possibility of further diminution.
Iota and jot both imply a minuteness suggestive of the character iota ι, the smallest letter of the Greek alphabet, while tittle, used chiefly in the phrase jot or tittle , implies a minuteness suggestive of a small diacritical mark such as the dot over an i; the three are used interchangeably to mean the smallest or most minute detail or amount.
Iota, however, sometimes denotes an insignificant amount, extent, or degree.