Imagine my surprise when I turned to the OED to find ‘Originally of a young woman: Full of activity, vigorous, lusty (obs.). Now of a person of either sex: Strongly and stoutly built, robust, sturdy.’
A quick Google showed that ‘strapping son(s)’ is still in common enough use (about 10,000 results).
A ‘strapping girl’ however produces many times more – about 80,000 – all of which seem to be of a kind that is unsuitable for an elderly lady to look at.
But 'strapping young woman' - about 90,000 results - seems respectable enough.
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