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it has two meanings. As a name of Krishna, Vāsudeva refers to the fact that he is the son of Vasudeva. But Vāsudeva has been a name of Vishnu long before the time of Krishna. For instance, this chapter of the Valmiki Ramayana refers to Vishnu's incarnation Kapila as Vāsudeva. How is this possible? It's because Vaasudeva has another meaning. As a name of Vishnu, it refers to the fact that since Vishnu is the supreme Brahman, he is the one who dwells in all beings and in whom all beings dwell. Here is what this chapter of the Vishnu Purana:

The term Vāsudeva means that all beings abide in that supreme being, and that he abides in all beings 

This chapter of the Udyoga Parva of the Mahabharata says much the same thing:

He is called Vasudeva in consequence of his enveloping all creatures with the screen of illusion, or of his glorious splendour, or of his being the support and resting-place of the gods. He is called Vishnu because of his all-pervading nature.

You asked for the etymological meaning of these terms. The meaning of Vasudeva given in the Vishnu Purana and the Mahabharata is already an etymological meaning, as should be clear from seeing the original Sanskrit. Here is the Udyoga Parva verse I quoted above:

vasanāt sarvabhūtānāṃ vasutvād deva yonitaḥ
vāsudevas tato vedyo vṛṣatvād vṛṣṇir ucyate

So the word comes from the root "Vas", which means to dwell or abide.