atom, n. monad, [molecule], [particle], [bit], [iota], [grain], [scrap], [scintilla].
atomic, a. molecular.
atonable, a. expiable. Antonyms: [unatonable], inexpiable.
atone, v. expiate.
atonement, n. expiation, [amends], [reparation], propitiation.
atoning, a. expiatory, propitiatory.
at short notice. summarily, promptly.
atrocious, a. [heinous], flagitious, [nefarious], [felonious], [infamous], [outrageous].
atrocity, n. heinousness, [enormity], nefariousness, flagrancy, [crime], [outrage].
attach, v. [affix], annex, append, subjoin; [distress], distrain, [seize].