(tīt) adjective
1. So closely held together or constructed as to be impervious to fluids; not leaky: a light roof; a tight vessel.
2. Firmly fixed or fastened in place; secure.
3. Fully stretched, so as not be slack; taut; tense: tight as a drum.
4. Strict; stringent: a tight schedule.
5. Fitting closely; especially, fitting too closely: said of a garment, shoe, cork, etc.
6. Colloq. Difficult to cope with; troublesome: a tight spot; a tight squeeze.
7. Colloq. Parsimonious; tight–fisted; close.
8. Characterized by a feeling of constriction: a tight cough.
9. Slang Drunk; intoxicated.
10. Evenly matched: said of a race or contest.
11. Difficult to obtain because of scarcity or financial restrictions: said of money or of commodities.
12. Straitened from lack of money or commodities: a tight market.
13. Yielding very little or no profit: said of a bargain.
—adverb
1. Firmly; securely: Hold me tight.
2. Closely; with much constriction: The dress fits too tight.
—to sit tight To remain firm in one's position; refrain from budging. [ME thight, appar. <Scand. Cf. ON thēttr dense.]
—tight′·ly adverb
—tight′ness noun

Impervious to: watertight.