Which of the following terms describes an inoffensive expression substituted for one considered offensive?

The term "euphemism" refers to a mild or inoffensive expression that is used to replace one which may be seen as harsh, blunt, or offensive. For example, saying "passed away" instead of "died" is a common use of euphemism. This practice allows speakers to address sensitive topics with more tact and consideration for the feelings of others. Euphemisms are particularly prevalent in discussions about death, illness, or other socially delicate subjects, as they help soften the impact of the language used.

The other terms do not fit this definition. A eulogy is a speech or tribute given in honor of someone who has died, glib refers to someone who speaks in an easy but often insincere or superficial manner, and goad means to provoke or annoy someone to stimulate some action or reaction. Thus, euphemism is the most accurate choice that aligns with the description provided in the question.