You raise some good questions.
Although humans discuss emotions a great deal, there doesn't seem to exist formal definitions for those concepts. Despite this, data can be collected that sidesteps this fact that can be useful: we can ask many people if they feel particular emotions and draw conclusions from that data. Still we must concede that a shared definition may not exist, which weakens these conclusions.
In the case of consciousness, we could ask many people if they thought that someone/something else was conscious, but it's not clear what value that would have.
More significantly, the utility of those concepts far precludes scientific definitions, those terms have been useful for thousands of years, and are essential to human society!
(Again, certainly not against definition, but be mindful of being too strict, too soon about it :) )
[1] The benefits of formalizing (human concepts) are subtle: like formalization in math, they help us build confidence that we're not building sand castle, dig deeper into theories of meaning, and use this to slowly improve lives of everyone. But like math, we've been doing it informally for very long, and a strict axiomatic formalization is still today relatively rare (although progressing with the aid of computer proof systems) for most fields. Still, the evolving standards for proof are likely essential for many of the deep theories we've achieved (probably including say modern logic and Godel's theories, algebraic geometry, functional analysis, etc.).