In the present-day world, suburbs generally means a "residential district located on the outskirts of a city, a sub-urban area" (the English word is derived from the Latin word urbanus, which means a city). "Suburb" is used by some versions of the Bible to translate the Hebrew word (pronounced) mig-raw-shaw, which meant open land around a city where flocks and herds were kept for pasture, while the people themselves lived in the city. In modern times, the suburbs are where people live outside the city; in ancient times, the suburbs were where sheep and cattle lived outside the city.
The original Hebrew word, mig-raw-shaw, was variously translated as "suburb" or something else, such as "common land," depending on the translation. An example of the difference, for Leviticus 25:34, from the classic King James Version of 1611 and the Revised Standard Version of 1952 (which is based on the American Standard Version of 1901):
"But the field of the suburbs of their cities may not be sold; for it is their perpetual possession" (KJV)
"But the fields of common land belonging to their cities may not be sold; for that is their perpetual possession" (RSV)
Other Scriptural references of the suburbs during Bible History, from the King James Version:
"And the cities shall they have to dwell in; and the suburbs of them shall be for their cattle, and for their goods, and for all their beasts" (Numbers 35:3 KJV)
"And they spake unto them at Shiloh in the land of Canaan, saying, The Lord commanded by the hand of Moses to give us cities to dwell in, with the suburbs thereof for our cattle. And the children of Israel gave unto the Levites out of their inheritance, at the commandment of The Lord, these cities and their suburbs." (Joshua 21:2-3 KJV)
References to future "suburbs" of the Holy City as given by God to Ezekiel The Prophet:
"In the visions of God brought he me into the land of Israel, and set me upon a very high mountain, by which was as the frame of a city on the south. And he brought me thither, and, behold, there was a man, whose appearance was like the appearance of brass, with a line of flax in his hand, and a measuring reed; and he stood in the gate. And the man said unto me, Son of man, behold with thine eyes, and hear with thine ears, and set thine heart upon all that I shall show thee; for to the intent that I might show them unto thee art thou brought hither: declare all that thou seest to the house of Israel." (Ezekiel 40:2-4 KJV)
"Afterward he brought me to the gate, even the gate that looketh toward the east [see Why Did They Face East?]: And, behold, the Glory of the God of Israel came from the way of the east: and his voice was like a noise of many waters: and the earth shined with his glory." (Ezekiel 43:1-2 KJV)
"And the five thousand, that are left in the breadth over against the five and twenty thousand, shall be a profane place for the city, for dwelling, and for suburbs: and the city shall be in the midst thereof." (Ezekiel 48:15 KJV)
"And the suburbs of the city shall be toward the north two hundred and fifty, and toward the south two hundred and fifty, and toward the east two hundred and fifty, and toward the west two hundred and fifty." (Ezekiel 48:17 KJV)
"It was round about eighteen thousand measures: and the name of the City from that day shall be, The Lord Is There" (Ezekiel 48:35 KJV)
Fact Finder: What physical, and spiritual, city did God designate to be the capital of the Kingdom of God?
See The Capital City and The City To Come. Also, The Throne Of God, From Heaven To Earth