形容詞 groundless:

1. without a basis in reason or fact
   同義詞：baseless, idle, unfounded, unwarranted, wild

1. Facts have proved these worries groundless.
   事實證明，這些憂慮是沒有根據(jù)的。
2. Of course, these implications would sly and groundless, and the opposition would realize it. But the voters might not. They would say where there's smoke there's fire.
   當然這些暗示是狡詐的，毫無根據(jù)的，反對派懂得這點。但選民不一定懂得，他們會說無風不起浪。

ground.less

adj.（形容詞）
Having no ground or foundation; unsubstantiated:
毫無根據(jù)的：沒有根據(jù)或基礎的；缺乏根據(jù)的：
例句：
groundless optimism.See Synonyms at baseless
毫無根據(jù)的樂觀參見 baseless

【引伸】
ground.lessly
adv.（副詞）
ground.lessness
n.（名詞）