The adjective pensive means “dreamily or wistfully thoughtful.” Someone who is in a pensive mood may be given to contemplation or reflection. While thoughtfulness is central to the meaning of pensive, the word itself suggests more feeling than the adjective thoughtful—and it is not used to convey consideration for others in the same way that thoughtful sometimes is. The attention of someone who is pensive is directed inward rather than outward.
Something that is unclear is not clear or definite. Another way to describe something unclear is to call it ambiguous; however, true to form, the meaning of ambiguous is not entirely straightforward! Ambiguous sometimes means obscure or indistinct, as in the case of a shape off in the distance, the outline of which is hard to discern. But when describing a statement, act, or attitude—or even a situation or relationship—ambiguous suggests a lack of clarity due to several meanings or possible interpretations.
To be overwhelmed by something is to be overcome by it completely in mind or feeling. A person might be overwhelmed with emotion on a momentous day. The verb inundate, while defined as “to overwhelm,” is used slightly differently. The primary meaning of inundate is “to flood” or “to cover or overspread with water.” Even when inundate is used in a context firmly planted on dry ground, the suggestion of a deluge, at least a figurative one as represented by great numbers of something, remains. For instance, if a columnist is inundated with letters from angry readers, he or she is swimming in negative feedback.