English Idioms and Phrases: Get a word in edgeways
Usually used negatively as in 'can't get a word in edgeways' or heard as edgewise replacing edgeways refers to a social situation. During a conversation you may try to add something, but if other people are talking a lot you can't even say what you want to say thus you can't get a word in edgeways.
"He was talking so much I couldn't get a word in edgeways'
The origin of this phrase is nautical. Edgeways means literally to move edge first, so for example when walking in a busy street you may turn to your side and walk more easily.
To 'edge forward' was an idea used in shipping referring to shallow or dangerous water. If the boat was at risk the captain would order the crew to 'edge forward' gently inch by inch.
To try and get word in edgeways refers to this process of trying to enter a word into a busy conversation where people are speaking a lot.