holding on very firmly
a tenacious grip
tending to stick or cling, esp to another substance
unwilling to desist or to give up on something; stubborn or persistent
able to recall things clearly for a long time; retentive
a tenacious memory
tenaciously adv
tenaciousness noun
tenacity /təʹnasiti/ noun
[Latin tenac-, tenax tending to hold fast, from tenēre to hold]