Used to summarize or give a concise opinion, often at the beginning of a sentence.
In a word, it's impossible.
To put it briefly, this movie was moving.
Standard kanji-kana mixed spelling.
Variant with 言 in kana; slightly less formal.
Phrase composed of 一言 (ひとこと, 'one word') + で (particle) + 言えば (conditional form of 言う, 'to say'). Literally 'if said in one word'.