Anna Massey had no dramatic training before appearing on stage in 1955 aged 17 in The Reluctant Debutante by William Douglas-Home. She took the part to Broadway, but then in the film it was taken by poor Sandra Dee, who, if she was born in 1942, was still only 16 when it was released in 1958, the last year debutantes were presented at court.
If it had been called The Reticent Debutante, the juvenile lead might have had fewer lines. I have noticed, with annoyance naturally, that reticent is now often used to mean ‘reluctant’. An article in the Telegraph about TikTok said that the businessman Zhang Yiming had been ‘reticent to give up control’.
One can see how ambiguity crept in. ‘He was reticent about discussing his private life’ still bears the meaning of ‘silent’, but being unforthcoming is only a step to being reluctant. To go the whole hog, the speaker has to give up the suggestion of silence, which the Latin origin reticere ‘to keep silent’ would demand. Perhaps something similar occurred with tacit. Its meaning of ‘silent’ developed a parallel sense of ‘implicit’ (because unspoken).
In his edition of Fowler’s Modern English Usage (1996), Robert Burchfield remarked with resignation that using reticent to mean ‘reluctant’ was ‘non-standard at present, but has an air of inevitability about it’. His suspicions were confirmed in 2010 when the Oxford English Dictionary revised its entry for reticent and quietly added the new sense: ‘reluctant to perform a particular action’. It had found evidence in America of this meaning from as early as 1875, not very long after the orthodox sense had become widespread in English during the 1830s.