| doubtable |
| dubitable |
| effete(adjective, weak, thin, delicate, shaky) |
| emasculated(adjective, weak, thin, delicate, shaky) |
| enervated(adjective, weak, thin, delicate, shaky) |
| enfeebled(adjective, weak, thin, delicate, shaky) |
| etiolated(adjective, weak, thin, delicate, shaky) |
| failing(adjective, weak, thin, delicate, shaky) |
| faint(adjective, weak, thin, delicate, doubtful) |
| farfetched(adjective, unreasonable, dubious, unlikely, flimsy) |
| fictional |
| fictitious |
| flabby(adjective, weak, poor, thin, delicate) |
| flat(weak, thin, incompetent, frail, puny) |
| for the birds(expression, idiom, extraordinary, unreasonable, dubious) |
| full of holes(expression, idiom, extraordinary, unreasonable, dubious) |
| halfhearted |
| hard of belief(expression, idiom) |
| harebrained(extraordinary, amazing, incredible) |
| helpless(adjective, weak, thin, delicate, shaky) |