Onomatopoeia for gulping or swallowing; also used to indicate a nervous 'gulp' or a tense moment.
面接の直前、彼はゴクリと唾を飲み込んだ。
Just before the interview, he gulped nervously.
司会者の質問に答える前に、出席者がゴクリと息を呑んだ。
Before answering the host's question, the attendee swallowed (gulped) in silence.
鍋のスープを一口飲んで、彼はゴクリと唾を飲み込んだ。
He took a sip of the pot's soup and swallowed in one gulp.