Incomplete in some sense, such as lacking a finite verb.
Dangling, drooping, hanging down or suspended.
Pending in various senses.
Either hanging in some sense, or constructed of multiple elements such as the voussoirs of an arch or the pendentives of a dome, none of which can stand on its own, but which in combination are stable.
Not settled, uncertain, of uncertain outcome; debatable, questionable, open to doubt.
Difficult to overcome, solve, or decide.
Contributing (especially if subtly) to discrimination (such as racism, sexism, homophobia, transphobia, or ageism).
a problematic analysis
A problem or difficulty in a particular field of study.