Excited. The most over-used word in the American language is now working it's way into proper English. Everyone is "excited" about everything. Enough already!

Backyard as a noun. Backyard is an adjective. So is backseat, freshwater, logon, logout, there are lots. they are adjectives. They are not nouns. English is complicated but it's not impossible. The worst offenders are authors and professional writers. They all look like semi-literate amateurs when they use adjectives as nouns. And their editors should be fired.