1) Abate 2) Ebb 3) Erode 4) Peter 5) Reduce 6) Vanish 7) Wane 1) Decrease 2) Degenerate, sink 3) Diminish 4) Diminish gradually 5) Dwindle away 6) Dwindle down 7) Exclusively Saxon word 8) Exclusively Anglo word 9) Fall 10) Gradually diminish 11) Grow less 12) Lessen 13) Slowly lessen in number 14) Taper off 15) To break up or disperse 16) To bring low 17) To fall away in quality 
• (n.) The process of dwindling; dwindlement; decline; degeneracy. • (v. t.) To make less; to bring low. • (v. i.) To diminish; to become less; to shrink; to waste or consume away; to become degenerate; to fall away. • (v. t.) To break; to disperse.
Dwin'dle intransitive verb [ imperfect & past participle Dwindled ; present participle & verbal noun Dwindling .] [ From Middle English dwinen to languish, waste away, Anglo-Saxon dwīnan ; akin to LG. dwinen ,...Dwin'dle noun The process of dwindling; dwindlement; decline; degeneracy. [ R.] Johnson. Dwin'dle transitive verb 1. To make less; to bring low. « Our drooping days are dwindled down to naught.» Thomson. 2. To break; to disperse. [ R.] Clarendon. 
[v] - become smaller or lose substance
get smaller
dwindle away verb become smaller or lose substance; `Her savings dwindled down`
[SAT terms] become smaller or lose substance[Literary terms] become smaller or lose substance