Across

3 young or youth
6 field
9 to increase
10 to grow up
16 to increase
17 unknown land
18 to overthrow
19 harvest
20 to explore

Down

1 to conquer
2 to expand
4 to investigate
5 dry land
7 to add
8 to fatten
11 to give citizenship
12 maturity
13 to explore, look out or spy
14 fat
15 expanse