TENUOUS

having little substance or strength

flimsy

weak

having a consistency
"a tenuous fluid"

very thin in gauge or diameter
"a tenuous thread"

lacking substance or significance
SYN - flimsy, fragile, slight, thin
"a tenuous argument"

"She was rather tenuous and he knew he could do better than that - find someone at his level willing to challenge him."

"It was a rather tenuous paper and he knew he had to do something to meat it up."

"All that was holding the shirt together was this tenuous string."