Wishy-washy is somebody who does not have a firm stance on something. Another expression for this would be "spineless" , meaning without a backbone, implying that there is no strength of character.

for example, wishy-washy wine - watery wine, wine with a lot of water. not very tasty, i suppose

i dont know yet

adj.缺乏力量或香味的, 缺乏特点或决心的