SYN: firm, established, secure, steady, constant, unwavering, durable, stanch, permanent, firmly fixed, solid, steadfast, steady, lasting, perpetual.
ANT: Infirm, tottering, weak, insecure, precarious, inconstant, wavering, frail, transient, ephemeral, evanescent, unstable.
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KEY: Stagnant.
SYN: Motionless, currentless, tideless, unflowing, uncirculating, still, dull, torpid, lifeless, quiescent.
ANT: Brisk, flowing, circulating, rapid, lively, agitated, seething, effervescent, restless.
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KEY: Staid.
SYN: Grave, demure, steady, sober, sedate.
ANT: Unsteady, flighty, indiscreet, wanton, unsedate, erratic, eccentric, agitated, discomposed, ruffled.