'sporadically-documented' originates from the combination of 'sporadic' and 'documented'. 'Sporadic' comes from the Medieval Latin 'sporadicus', meaning 'scattered', and 'documented' from the Latin 'documentum', meaning 'example, proof'.

'sporadicus' transformed into the English word 'sporadic', and 'documentum' evolved into 'documented', eventually forming the compound adjective 'sporadically-documented'.

Initially, 'sporadic' meant 'scattered or isolated', and 'documented' meant 'recorded or written down'. Together, they convey the idea of being recorded in a scattered or irregular manner.