pulpityoudaoicibaDictYouDict[pulpit 词源字典]
pulpit: [14] Classical Latin pulpitum, a word of unknown origin, denoted ‘platform, stage’. This sense was originally carried over into English (Miles Coverdale, in his 1535 translation of II Chronicles 6:13, wrote ‘Salomon had made a brasen pulpit … upon the same stood he’, where the 1611 Authorized Version was later to have ‘Solomon had made a brasen scaffold … and upon it he stood’).

But it was eventually swamped by a subsidiary sense which emerged in medieval Latin: pulpitum had been applied particularly to platforms on which people stood to speak in public, and in ecclesiastical usage it came to denote a ‘raised structure on which preachers stand’.
[pulpit etymology, pulpit origin, 英语词源]
rostrumyoudaoicibaDictYouDict
rostrum: [16] Latin rōstrum originally meant ‘beak’ or ‘muzzle of an animal’ – it was derived from the verb rōdere ‘gnaw’ (source of English corrode [14], erode [17], and rodent [19]). The word was also applied metaphorically to the ‘beaklike’ prows of ships. In 338 BC the platform for public speakers in the Forum in Rome was adorned with the prows of ships captured from Antium (modern Anzio), and so in due course all such platforms came to be known as rostra – whence the English word.
=> corrode, erode, rodent
scaffoldyoudaoicibaDictYouDict
scaffold: [14] Historically, scaffold and catafalque [17] ‘coffin-stand’ are virtually the same word. Catafalque comes via French catafalque and Italian catafalco from Vulgar Latin *catafalcum, a word of uncertain origin. Combination with the prefix ex- produced *excatafalcum, which passed into English via Old French eschaffaut and Anglo-Norman *scaffaut.

The word originally denoted any sort of platform, and did not narrow down to ‘platform for executions’ until the 16th century. The derivative scaffolding, a term which originally alluded to the platforms set up around a building rather than to poles supporting them, also dates from the 14th century.
=> catafalque