unanimous
"panacea"
There is no one-word substitute in English for "son-in-law."
The word you want is florist.
Sportsmanship is a word substitute for spirit of game
Not sure if this is the word you seek, but another word for "last name" is surname.
The word metalworking is one word.
eat, use
One possible substitute for "their" is "his" or "her" depending on the gender of the person/people being referred to. Another substitute can be "its" when referring to a non-human object or entity.
The word that works is idiot.
Elevate
Traditionalist
Omnipresent