If it's "loaded," it's because of the claim that happiness is an objective property: "of, relating to, or being an object, phenomenon, or condition in the realm of sensible experience independent of individual thought and perceptible by all observers : having reality independent of the mind ..."
Nobody denies that "happiness" is a real thing. The question is, rather, whether a state of happiness satisfies the criteria of objectivity.
Similarly, nobody denies the existence of a sex drive. But it is not a completely objective thing, either. Consider: Most guys don't want to have sex with every woman they see, and they don't even want to have sex all the time. The criteria for what makes you want to have sex with one woman and not another ... or now but not yesterday ... those are bewilderingly complicated, to say the least, and they're different for different people.
It's not enough to note the objective fact that there's a sex drive, or a human capacity for "happiness," however defined; the thing is that it operates on highly subjective criteria.
(Come to think of it, a person who is convinced that the mind is in the brain, and thoughts are located in the brain, would find it objectionable too.)
Of course, the dictionary exists to get us to use our words straight. I'm discussing a point that's germane to a philosophy class, so it shouldn't be construed as a criticism of the dictionary.