Os suffixos FUL e LESS geralmente são acrescentados a substantivos, formando assim adjectivos.
E podemos dizer que,na maioria das vezes, são opostos. Enquanto FUL (um L só) dá a idéia de cheio, tendo “muito” LESS dá a idéia de sem, não tendo.
Mas isso não quer dizer que vocês possam sair colocando FUL e LESS em todo substantivo, criando contrários.
➡ Vale lembrar que o contrário de BEAUTIFUL não é BEAUTILESS!
careFUL ➡ trying to avoid mistakes, accidents
careLESS ➡ not paying enough attention
harmFUL ➡ causing harm (damage/injury)
harmLESS ➡ not causing harm
(un) helpFUL ➡ (not) giving help, being useful
helpLESS ➡ unable to act or defend oneself
hopeFUL ➡ feeling or inspiring optimism
hopeLESS ➡ without hope – terrible
painFUL ➡ causing pain
painLESS ➡ not causing pain
powerFUL ➡ having a lot of power or strength
powerLESS ➡ not having power
thoughtFUL ➡ caring and considerate
thoughtLESS ➡ not caring and inconsiderate
useFUL ➡ effective in helping you do something
useLESS ➡ not helpful or effective in any way
endLESS ➡ having or seeming to have no end
grateFUL ➡ showing gratitude or appreciation
(un) successFUL ➡ (not) having success
skillFUL ➡ having or showing great skills
worthLESS ➡ having no value