'occasionally-documented' originates from the combination of 'occasionally' and 'documented'. 'Occasionally' comes from the Latin 'occasio', meaning 'a happening' and 'documented' from the Latin 'documentum', meaning 'example, proof'.

'Occasionally' evolved from the Latin 'occasio' through Old French 'occasion', and 'documented' from Latin 'documentum' through Old French 'document'.

Initially, 'occasionally' meant 'a happening' and 'documented' meant 'example, proof'. Over time, 'occasionally-documented' evolved to mean 'recorded at irregular intervals'.