prolonged  - prolongado 

lengthy  - largo y pesado, prolongado, largo 

long  - largo, prolongado 

to prolong  - prolongar 

to extend  - extender, tender, extenderse, prolongar, prorrogar, agrandar, ampliar, aumentar, dar, ofrecer 

to lengthen  - alargar, alargarse, crecer, prolongar, extender