Usage: 5 forms in 13 verses
Form Translated As     In Verse(s)
ηρρώστησεν Hezekiah became ill LXX.2Chr.32.24
Hezekiah was infirm LXX.2Kgs.20.1LXX.2Kgs.20.12
became ill LXX.1Kgs.17.17
was ill LXX.1Kgs.14.1
ηρρώστησε became as ill LXX.2Sam.13.6
became ill LXX.2Kgs.13.14
he was ill LXX.2Sam.12.15
was infirm LXX.2Kgs.1.2
ηρρώστει he was infirm LXX.2Kgs.8.29LXX.2Chr.22.6
αρρωστών infirm LXX.2Kgs.8.7
αρρωστείν to be ill LXX.2Sam.13.2

Liddell-Scott-Jones

ἀρρωστέω (arrōsteō) be ill G:V

ἀρρωστέω-έω,

to be unwell, [ἀρρωστέωίην, ἀρρώστημα, 5th c.BC: Hippocrates Medicus “Κωακαὶ προγνώσιες” 579, 4th c.BC: Aristoteles Philosophus “Rhetorica” 1372a28.">Refs 5th c.BC+]