From Longman Dictionary of Contemporary Englishfor longfor long[usually in questions and negatives] for a long time Have you known them for long? I haven’t seen her for so long that I’ve forgotten what she looks like. → long
Examples from the Corpus
for long• Have you been working here for long?• Have you known the Garretts for very long?• He'll have to stay in hospital, but not for long.• I haven't known them for very long.• I hope his speech doesn't go on for long. 