mere-strǣt, f.n: the road which the sea furnishes; literally, ‘mere-street’, the sea.
Image from a blog post by Hermano Juancito: Christ is depicted twice in this miniature. On the left he is sleeping during a storm and Peter is trying to wake him up. On the right he blesses and calms the waves of the mere-strǣt. There appear to be two creatures (flying fish?) in the sky above. If anyone knows where this is from, please comment below, because that is all the info I have on it.
Note (07/06/15): Helen Anderson notes the resemblance of these fish to the Saint-Pierre fish in her comment below. Here’s an image of one, which comes from an interesting blog post about it from Behind the French Menu.