Leader
Boss, Chief
noun
Someone who has territory under their sleeve is the leader. They're the boss of all this territory because they say so, and because they shoved it all into their big sleeves.
りょうしゅう
This is a jukugo word that uses the on'yomi readings of the kanji. You've learned them already, so you should be able to read this on your own!
領袖の言うことは絶対だ。
What a boss says is absolute.
その政治家こそが、党の領袖だ。
That politician is the leader of the party.
「領袖」と言う言葉は、現代では、政治的な使われることが多い。
These days, the word "leader" tends to be used in the political sense.