'edge'とはどんな意味？

まずは『ハリー・ポッター』、
Frank edged closer and closer, he was able to see a narrow slice of the room beyond.
(p.11, the goblet of Fire)

George made to shut the door to drown the noise, but before he could do so, a house-elf edged into the room.(chap.6, the Order of the Phoenix)

逆の方向への動き？
That's what we're putting in the adverts, anyway,' whispered Fred, who had edged over out of Mrs Weasley's line of vision and was now sweeping a few stray Doxys from the floor and adding them to his pocket.(chap.6, the Order of the Phoenix)

intoと結んで論文にも登場。
In the mid- 1980s the theory edged into the mainstream when he and other researchers established that all mammals, so far as anyone knows, have naturally in their cells a gene encoding the prion protein.
(Scientific American, January 1998)

こちらは「名詞」。さてどんな意味？

『ハリー･ポッター』では、

"I found you," said Wormtail, and there was definitely a sulky edge to his voice now. "I was the one who found you. I brought you Bertha Jorkins."(p.15, Fire of the Goblet)

これが入試問題だと、ちょっと感じがちがうかな？
..., he thinks that DNA's original selective edge was that it allowed viruses to avoid their host's defences.　(Nature2006年1月12日号[2007年度、東大・後期（評論）])