In Italian the absolute superlative is obtained by adding the ending -issimo (and all its forms) to the stem of the adjective. For example:
simpatico —> simpaticissimo
nice —> very nice
Using the adverbs molto / estremamente / assai / oltre modo (very, extremely, quite, really) before the adjective. For example:
simpatico —> molto simpatico
nice —> very nice
Repeating the adjective describing it twice. For example:
Era un ragazzo alto alto —> He was an extremely tall kid
Using specific prefixes which are used to express the highest degree of a quality such as arci- , sopra-, sovra-, stra-, ultra-. For example:
Era un ragazzo strasimpatico —> He was a super funny kid
Have a look at some expressions used to indicate the highest degree of a quality:
Stanco morto / knackered
Bagnato fradicio / soaking wet
Ubriaco fradicio / blind drunk
Magro da far paura / terribly thin
Nuovo di zecca / Brand-new
Nuovo fiammante / Mint
Pieno zeppo / Jam-packed (crammed with)
Vecchio decrepito / An old fossil