Boyd’s Bible Dictionary:

(my people). Applied figuratively to the Israelites (Hos. 2:11Say ye unto your brethren, Ammi; and to your sisters, Ru-hamah. (Hosea 2:1) marg.).

Concise Bible Dictionary:

Name applied to Israel figuratively. It signifies “my people,” and is used with the negative in Lo-ammi, “not my people” (Hos. 1:99Then said God, Call his name Lo-ammi: for ye are not my people, and I will not be your God. (Hosea 1:9)).

Jackson’s Dictionary of Scripture Proper Names:

my people