Definition of tightest:
(adj) :
Firmly held together; compact; not loose or open.
(adj) :
Unyielding or firm.
(adj) :
Under high tension; taut.
(adj) :
(colloquial) Scarce, hard to come by.
(adj) :
(informal, figurative, of persons or relationships) Intimate, close, close-knit, intimately friendly.
(adj) :
(slang, figurative, usually derogatory) Miserly or frugal.