Tiny particle (4)
'tiny particle' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for atom that I've seen before include "An explosive particle as in bomb" , "type of bomb" , "Basic unit of a chemical element" , "Very small object or amount" , "Minute fragment" .)
'tiny particle' is the definition.
(type of subatomic particle)
This is the entire clue.
(Other definitions for neutrino that I've seen before include "Subatomic particle, now said to travel faster than light" , "This barely affects anything" , "Small piece of matter" , "Minute item lacking mass" , "Tiny thing not charged" .)
'tiny particle' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for molecule that I've seen before include "Small particle of matter" , "Small group of atoms" , "atomic group" , "Smallest unit of compound" , "Smallest particle of a substance" .)