Usage: 5 forms in 16 verses
Form Translated As     In Verse(s)
αρρωστίασ infirmity LXX.2Kgs.1.2
my illness LXX.2Kgs.8.8 • LXX.2Kgs.8.9
sickness LXX.2Chr.21.15
αρρωστίαν with his illness LXX.2Kgs.13.14
αρρωστίαισ sicknesses LXX.2Chr.21.15 • LXX.2Chr.21.19
αρρωστία αυτού his infirmity LXX.2Chr.16.12
αρρωστία a sickness LXX.2Chr.21.18 • LXX.Eccl.5.13
his illness LXX.Ps.41.3
his sickness LXX.2Chr.21.19
illness LXX.1Kgs.17.17
sickness LXX.Eccl.5.16 • LXX.Eccl.5.17 • LXX.Eccl.6.2

Liddell-Scott-Jones

ἀρρωστία (arrōstia) illness G:N-F

ἀρρωστία-ία, ἡ,

weakness, sickness, [Refs 5th c.BC+]: especially lingering ailment, bad state of health, [Refs 5th c.BC+]

__2 moral weakness, [Refs 4th c.BC+]; loss of morale, [Refs 5th c.BC+] lack of eagerness to serve, [Refs 5th c.BC+]