Airmail is the system of sending letters, parcels, and goods by air.
...an ~ letter...
Goods are generally shipped by ~.
N-UNCOUNT: oft N n, by N
Airmail is the system of sending letters, parcels, and goods by air.
...an ~ letter...
Goods are generally shipped by ~.
N-UNCOUNT: oft N n, by N
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012