Deficiency
Noun and する verb
けつじょ
ビタミンB1が欠如すると、脚気になるかもしれないですよ。
A Vitamin B1 deficiency might cause beriberi.
You lack likeness to anything out there. You totally lack something that gives you likeness. It's a deficiency, or something.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.