How would you best describe something that is "furtive"?

The term "furtive" is best described as secretive and sly. It conveys a sense of stealth or a desire to avoid being noticed, often implying that there is something hidden or concealed. When someone is acting furtively, they may be trying to keep their actions or intentions from being observed by others, which can suggest a level of deceit or craftiness.

For instance, if a character in a story is observed doing something furtively, it likely means they are sneaking around or acting in a suspicious manner, trying to avoid detection. This characteristic aligns perfectly with the definition of "furtive," making the option of secretive and sly the most accurate choice.