I found this word in “The Solitary Cyclist” in The Greatest Adventures of Sherlock Holmes. I should have guessed the meaning by the context, but its so simple, and I had no clue.

Greensward – grass-covered ground (see? simple)

Usage: “We had broken suddenly into a lovely glade of greensward surrounded by ancient trees.”

(You will have to read “The Solitary Cyclist” to find out why Holmes and Watson were breaking so suddenly into a grassy area. It’s part of the plot twist of the story.)