What is Shakespeare refering to when he says "O thou weed,

Who art so lovely fair and smell'st so sweet
That the sense aches at thee" in Othello? I havent read this, but I was wondering, is he talking to a person, or a plant?

Neither, he was talking about an unwanted emotion, feeling.

In the passage you mentioned from Othello, Shakespeare is using metaphorical language to describe a person rather than a plant. The line "O thou weed, Who art so lovely fair and smell'st so sweet" is an insult directed towards someone.

To understand the meaning and context of this line, it is important to consider the overall scene and themes of the play. Othello is a tragedy written by Shakespeare in which the title character, Othello, is a Moorish general in the Venetian army who falls victim to manipulation and jealousy.

In this particular scene, Othello is speaking to Desdemona, his wife, and accuses her of being unfaithful. By referring to her as a "weed," Shakespeare is suggesting that Desdemona appears to be beautiful and attractive on the surface, but underneath, she is harmful, unwanted, and disruptive to Othello's life and happiness.

The metaphor of a "weed" implies that Desdemona is a threat or a disturbance in Othello's perception. Shakespeare uses this metaphor to emphasize the contrast between the outward appearance of Desdemona's beauty and the pain Othello feels due to his suspicions and jealousy.

It is crucial to read or watch the play in its entirety to fully understand the complex dynamics and metaphors employed by Shakespeare. Taking lines out of context can sometimes lead to misunderstandings, so exploring the entire plot and themes of Othello would provide a more comprehensive understanding of the passage you mentioned.