ammunitionyoudaoicibaDictYouDict
ammunition: [17] Ammunition is one of many words which resulted from a mistaken analysis of ‘article’ plus ‘noun’ (compare ADDER). In this case, French la munition ‘the munitions, the supplies’ was misapprehended as l’ammunition, and borrowed thus into English. At first it was used for military supplies in general, and it does not seem to have been until the beginning of the 18th century that its meaning became restricted to ‘bullets, shells, etc’.

The word munition itself was borrowed into English from French in the 16th century. It originally meant ‘fortification’, and came from the Latin noun mūnītiō; this was a derivative of the verb munīre, ‘defend, fortify’, which in turn was based on the noun moenia ‘walls, ramparts’ (related to mūrus ‘wall’, the source of English mural).

Also from munīre, via medieval Latin mūnīmentum, comes muniment [15], a legal term for ‘title deed’; the semantic connection is that a title deed is a means by which someone can ‘defend’ his or her legal right to property.

=> muniment, munition, mural
boulevardyoudaoicibaDictYouDict
boulevard: [18] Boulevard is a frenchified version of German bollwerk ‘fortification’ (the corresponding anglicized version is bulwark). The meaning of the French word, apparently quite divergent from that of bulwark, comes originally from the practice of constructing walkways along the top of demolished ramparts.
=> bulwark
intervalyoudaoicibaDictYouDict
interval: [13] The val- of interval represents Latin vallum ‘rampart’ (source of English wall) – so etymologically the word means ‘space between ramparts’. That was the original sense of its Latin ancestor, intervallum, but already in the classical period the metaphorical ‘gap in time, pause’ was developing.
=> wall
wallyoudaoicibaDictYouDict
wall: [OE] Wall was borrowed into Old English from Latin vallum ‘rampart’. This originally denoted a ‘stockade made of stakes’, and it was derived from vallus ‘stake’. German wall, Dutch wal, and Swedish vall, also borrowings from Latin, preserve its meaning ‘rampart, embankment’, but English wall has become considerably wider in its application. An interval is etymologically a space ‘between ramparts’.
=> interval
interval (n.)youdaoicibaDictYouDict
early 14c., from Old French intervalle (14c.), earlier entreval (13c.), from Late Latin intervallum "space, interval, distance," originally "space between palisades or ramparts," from inter "between" (see inter-) + vallum "rampart" (see wall (n.)). Metaphoric sense of "gap in time" was present in Latin.