One should always be open to adverbs one has not met before. Recently, I particularly enjoyed meeting Vicatim.
Its meaning of course, is not obscure. It comes from 'Vicus', which means the shanty town which would tend to grow up arround a Roman military establshment for families, tradesmen, and military hangers-on. I recall, years ago, when I was doing Duty for the (Anglican) parish of Burgh-by-Sands, on Hadrian's Wall, we had a group of archaeologists in the Rectory garden, excavating the 'vicus' which accompanied the Wall Fort of 'ABALLAVA'. They were led by a blond Welshman ... yes ...
Archaeologists call the villages which grew up in such contexts 'vici'. Whether this is what the Romans called them, or whether the usage is a convenient modern academic adaptation, I do not know. But, certainly in the area of the Wall, some of these vici, at least, became quite significant architecturally. Our Family enjoyed lending a hand and seeing what emerged from the ground.
So, if we were to talk about a procession round the vicus, vicus would mean the unofficial township around an important Roman site. We would be thinking about a procession ... perhaps, at Aballava, in honour of Hercules and the Deity of the Emperor (an altar with that dedication has been found there). And we could conveniently talk, adverbially, about such a procession being done vicatim, if we expected it to go piously winding round the streets and alley-ways of the township,
Which brings me very naturally on to the subject of Apostolic Constitutions.
Not that I claim particular knowledge of this subject; but, often enough, I have seen that phrase attached to what look to me ... am I right, or am I right? ... like really important bits of the Church's law ... new codes of Canon Law ... new translations of Scripture ... erections of Ordinariates ...
I am refering here to an Apostolic Constitution (Ubi Primum) of 2 October 1898 ... or, for the mathematically slower among you, of the Sixth before the Nones of October. It bears the authority of Pope Leo XIII. It contains, most importantly, norms for Rosary Sodalities.
Not that these norms are revolutionary: they mostly reassert legislation of S Pius V (1569); Gregory XIII (1573); Paul V (1608).
And what they assert (XIV), among other enactments, is that on the first Sunday of each month, each Sodality should hold a pompa of our blessed Lady.
And that they should do so vicatim.