Intangible and ethereal mean something that is not physical, cannot be felt by touch. The ethereal or intangible often used when talking about spirituality or even emotions. As suggested in the word, intangible is the opposite of ‘tangible’, something physical or measurable. ‘Love’ is a good example. As a feeling ‘love’ could be described as intangible. However, in relationship it is important to make that person feel loved in tangible ways such as giving gifts, spending quality time together, etc.

In a legal context, "intangible property" could be something like an intellectual property right, which is not a physical thing so you cannot touch it. The word is also used in other ways as per Peter Lilly's answer.