Tehuantepec, Isthmus of
geographical name
Te·huan·te·pec, Isthmus of tā-ˈwän-tā-ˌpek 
the narrowest section of Mexico, between the Gulf of Tehuantepec (on the Pacific side) and the Bay of Campeche; 137 miles (220 kilometers) wide at its narrowest point
- in the bargain
- in the beginning
- in the belief that
- in the best light
- in the black
- in the blink of an eye
- in the bud
- in the buff
- in the business of
- in the bygoing
- in the can
- in the cards
- in the care of
- in the catbird seat
- in the chips
- in the clear
- in the clouds
- in the clover
- in the club
- in the clutch
- in the cold light of day
- in the comfort of one's own home
- in the company of
- in the control of
- in the course of time