Surround, environ, encircle, circle, encompass, compass, hem, gird, girdle, ring can mean to close in or as if in a ring about something.
Surround is a general term without specific connotations; it implies enclosure as if by a circle or a ring.
Often the term denotes not a literal enclosure but something which forms the circumstances, the environment, or the border of something.
Environ also implies enclosure as if by a circle or a ring, but it often differs somewhat from surround in carrying a clearer implication of the permanent or continuing existence of what environs; thus, “a nation environed by foes” does not clearly imply as immediate danger as “an army surrounded by foes” does, but the former does suggest a persistent or ever-present danger in a way that the latter cannot. The difference is often slight but usually perceptible.
Encircle is not quite the equal of surround though very like it in meaning and often interchangeable with it; it more definitely suggests an enclosing circle and therefore often is suited to a more concrete use; in this sense it is often equal to circle .
Also, encircle and circle may denote to proceed in a circle about something, a meaning unknown to surround .
Encompass suggests something that closes in or shuts off a place or person; it often also suggests a motive (as protection or homage or hostility).
Compass implies a being surrounded or encompassed usually by something that covers and protects or by something that weighs down upon and depresses.
Hem, usually followed by an adverb and especially in , carries the strongest implication of confinement or of perfect enclosure of any of these words and often suggests difficulty or impossibility of escape.
Gird and girdle both basically apply to an encircling of the waist with a belt or girdle.
Gird is sometimes preferred when the meaning of to surround or encircle is expressed and the idea of a strong or insuperable barrier is implied.
Girdle , on the other hand, tends to imply an encirclement suggestive of a belt or sash or constituting a zone and seldom connotes a tight or confining quality in what encircles.
Ring carries a vivid picture of formation in a ring, but beyond this it has no particular implication. It is frequently chosen as a picturesque word in the senses of surround , encircle , and hem in .