An armful is how much you can hold in one arm, or in both arms together — a load against your chest. An armful of books, an armful of washing, an armful of flowers.

an armfulAn armful is how much you can hold in one arm指的是你一隻手臂，or in both arms together或雙臂合起來可以抱住的量——a load against your chest一份抱在胸前的東西。an armful of books『一抱書』、an armful of washing『一抱要洗的衣服』、an armful of flowers『一抱花』。

It is a homely, everyday word, not a science word. The -ful here does not mean “full of arm”; it means “as much as the arm can take,” the same trick as handful and mouthful.

it is a homely, everyday word這是個很生活化的日常用字，not a science word不是科學用詞。the -ful here does not mean "full of arm"這裡的-ful不是指『裝滿了手臂』；it means "as much as the arm can take"意思是『手臂能拿的量』，the same trick as handful and mouthful跟handful、mouthful用的是同一種造字方式。

You can say two armfuls if you made two trips. Though actually, nobody is measuring with a ruler: “an armful” is rough, like “a lot that I can carry.” It is a noun.

if you made two trips如果你搬了兩趟，you can say two armfuls可以說two armfuls。though actually不過其實，nobody is measuring with a ruler沒有人會拿尺去量："an armful"『an armful』 is rough是概略的說法，like "a lot that I can carry"就像『一大堆我抱得動的東西』。it is a noun它是名詞。

You do not say “I am armful,” and it is not the same -ful as in beautiful or harmful, which describe a quality.

you do not say "I am armful"你不會說『I am armful』，and it is not the same -ful而且這裡的-ful不一樣 as in beautiful or harmful跟beautiful、harmful裡的-ful，which describe a quality那些是用來形容一種性質。