aniyan..!
We can call her aniyathi in Malayalam.
brother= sahodaran( not commonly used in spoken malayalam) Elder brother = chettan younger brother = aniyan
You say "ചേട്ടന്" (chettan) to refer to an older brother and "അച്ഛന്" (achchan) to refer to a younger brother in Malayalam.
meaning of the Malayalam word anujan is -- " YOUNGER BROTHER "
Both Anna and chettan are used for older brother. Younger brother is aniyan.
In Malayalam, elder brother is called "ചേട്ടന്" (chettan).
sister = sahodari older sister = chechi younger sister = anujathi
You would call your husband's younger brother a brother-in-law.
" Ikka "
sahodharan
chetan.
In Malayalam 'chettan' means elder brother and 'aniyan' means younger brother