Abarim Publications' online Biblical Greek Dictionary
The noun λιμην (limen) means harbor or port, with an emphasis on safety and shelter (in stead of, say, commerce). In Homer's Odyssey, for instance, occurs the phrase λιμενες θαλασσης (limenes thalasses), literally meaning "harbor from the sea" but by implication "shelter from the sea". As such, our word is used metaphorically in the sense of haven, retreat, refuge or even simply a (safe) gathering place.
Hence our word is used in phrases like "a haven of friendship", "a haven from ills", even the "harbor of Hades". Some ancient writers used the noun λιμην (limen) as synonym for αγορα (agora), denoting a place of assembly or market. Sophocles even spoke of the "bounteous harbor" that suited Oedipus both as child and as father, and with which he doubtlessly meant his mother's embrace or even womb.
Our word is used only once in the narrative of the New Testament, namely in Acts 27:12, where the harbor of Fair Havens (same word) is said to be not suited for wintering.