These are examples of blends, or what Humpty Dumpty called ‘portmanteau’ words (Through the Looking Glass by Lewis Carrol):
web + log = blog international + network = internet internet + etiquette = netiquette cybernetics + space = cyberspace
These blends have become established pretty quickly, others are so much older the original blending is often forgotten:
because = by + cause electrocute = electrical + execution fortnight = fourteen + nights goodbye = God + be + (with) ye
This morning, dropping her pyjamas on the floor, my daughter declared she was storing her clothes in her “floordrobe”. That’s one portmanteau word I hope doesn’t catch on!