first officer

officer second in command to a captain on a merchant ship （商船上的）大副.

firm, firmament, firmly, firmness, first, first aid, first and foremost, first balcony, first base, first class, first cousin, first degree, first finger, first floor, first gear, first lady, first name, first night, first of all, first offender, first or last, first refusal, first school, first-aid, first-born, first-class, first-day cover, first-footing, first-fruit, first-hand, first-rate, firsthand, firstly, firth, fiscal, fiscal year, fish, fish and chips, fish cake, fish finger (US fish stick),