Vraag:
Is 'sick' correct in plaats van 'ill' zoals in I have been sick for two months?

Antwoord:

‘Sick’ in de betekenis van ‘having a disease’ is correct maar blijkt vaak fout gerekend te worden. Dat komt omdat vroeger altijd geleerd werd: a sick child, maar: The child was ill. Al tientallen keren ben ik in betrouwbare Brits-Engelse documenten ‘sick’ tegengekomen in de betekenis van ‘ill’.
Deze betekenis van 'sick' is ook te vinden in de volgende bronnen:

Grammaticaboeken:

English Grammar for Higher Education (Noordhoff)
“Note that sick can be used in the meaning of ill without a following noun:
He was ill/sick."

Cobuild English Usage (Collins)
“Ill and sick are both used to say that someone has a disease or some other problem with their health: My uncle is very sick."

Practical English Usage (Oxford)
"Ill and sick are both used to mean ‘unwell’:
George didn’t come in last week because he was ill/sick."

Collins Cobuild Advanced English Dictionary (Collins)
"If you are sick, you are ill:He is very sick; he needs medication."

Kranten:

“Lola is showing she still has the will to live, although she is very sick,” (The Times 20-1-12)

"He did not look fit but he did ring in sick a couple of days later. He’s been sick all week, lost three kilos.” (The Times 11-12-11)

“We’ve told the Thailand organisers, they know he’s been sick for a few weeks. He wants to play there but I think he’ll make a decision tomorrow night." (The Times 9-12-11)

"A premature baby, described as having been very sick, died at Salford Royal Hospital in late December. It was discovered that the child had aspergillus." (The Times 15-2-08)

"Separated from her husband, who also has Aids, she has been sick for the past two years but is now so weak that her mother has to care for her." (28-12-2002 The Times)