Tenuous is an adjective.

The Latin root for the words tenuous and attenuate is the word tenuis meaning thin.

Their relationship had always been tenuous, so it wasn't difficult for her to cut her chronically alcoholic sister out of her life completely.

Plans for the picnic are tenuous because it looks like it might rain.

adjective

1.

thin or slender in form, as a thread.

2.

lacking a sound basis, as reasoning; unsubstantiated; weak: a tenuous argument.

3.

thin in consistency rare or rarefied.

4.

of slight importance or significance; unsubstantial: He holds a rather tenuous position in history.

5.

lacking in clarity; vague: He gave a rather tenuous account of his past life.