To have in one's grasp
grasp, grip, clutch, carry, embrace, clench, cling to, detain, enclose, restrain, confine, check, take hold of, contain, hold down, hold onto, not let go, never let go, hang on, have a firm hold of, squeeze, press, secure, hug, handle, fondle, have in hand, keep in hand, keep fast, retain, keep, keep a grasp on, maintain a grasp on, clasp, hold fast, hold tight, keep a firm hold on, tie, keep close, unite, palm, take, catch, clinch, fasten upon, cradle, have an iron grip on*, hang on to*; see also seize 1.
Antonyms let fall, release*, let go.
To have in one's possession
keep, retain, possess; see maintain 3, own 1.
To remain firm
resist, persevere, keep staunch; see continue 1, endure 2.
To adhere
attach, cling, take hold; see adhere, fasten 1, stick 1.
To be valid
exist, continue, remain true, have bearing, be the case, endure, be in effect, operate, be in force; see also be 1.
Antonyms stop*, expire, be out-of-date.
To believe
regard, aver, judge; see believe 1, think 1.
To contain
have the capacity for, accommodate, be equipped for; see contain 1, include 1.
To support; often used with up
sustain, brace, buttress, prop, lock, stay, shoulder, underpin, uphold, underprop, shore up, bear up, bolster up; see also support 1. See syn. study at contain.