A neologism coined by Ellanto for “seige”, posted on 2024-05-15 in the Vinyë Lambengolmor Discord Server (VLDS) as a noun form of [ᴺQ.] ahta- “narrow” in its more specialized meaning “besiege”. I would use the less opaque noun ostampë for “siege”, but would retain ahtassë for the more general sense “narrowing”.