Jamieson, Fausset & Brown

Prisca and Aquila-- (Act 18:2-3; Rom 16:3-4; Co1 16:19, written from Ephesus, where therefore Aquila and Priscilla must then have been). household of Onesiphorus--If he were dead at the time, the "household" would not have been called "the household of Onesiphorus." He was probably absent (see on Ti2 1:16).