Originally this phrase, spelled ‘strait laced’ meant constricted or narrow but, more specifically, wearing a bodice or corsets tightly laced. Today it is spelled ‘straight laced’ and means excessively rigid in behavior, morals, or moral judgement.
‘Strait’ is still used in expressions like ‘strait and narrow,’ ‘dire straits,’ ‘strait-jacket,’ and ‘straitened circumstances.’ The meaning of both spellings becomes clear when we know that ‘strait’ means, not ‘free from curvature,’ but ‘tight.’ That usage goes back to the 13th century.
‘Strait’ derives from Latin stringere, to bind tightly, which is the root of ‘constrain,’ ‘strict,’ and ‘stringent,’ among others. That’s why that obsolete method of restraining lunatics called the straitjacket is correctly spelled in that way. These days we know it mainly as a narrow stretch of navigable seaway, as in the Straits of Gibraltar. Its other current meaning refers to a situation of difficulty, distress, or need, but usually appears only in the fixed phrase ‘dire straits,’ (great need or extreme danger), or ‘straitened circumstances,’ for a person who is living in poverty.
The expression ‘strait-laced’ is found first in print, in a Middle English text — John Lydgate’s My Fayr Lady, circa 1430. In the poem, for comic effect, Lydgate describes his beloved variously as ‘lyke as an olivaunt [elephant] and with greet square shulderys brood’ (great broad, square shoulders).
In the 16th century, ‘strait-laced’ began to be use figuratively to refer to people who were rigid in their beliefs and thinking. Thomas Martin’s religious tract The Marriage of Priestes, 1554, displays that usage:
“He had to doe with certaine holy and straite lased heretikes, whiche denied it to be lawful for a Christian man after his baptisme to retourne to his wife.”
In the 18th and 19th centuries, fashion dictated that women of quality wore exceptionally tightly laced corsets to emphasize their hourglass figures. The impression that we now have of ladies of the prim and formal Victorian upper classes is that they were strait-laced in more ways than one.
Our phrase ‘straight and narrow’ was originally ‘strait and narrow.’ But there is a common sense image behind ‘straight and narrow’ that has helped it to be accepted, since it can be said to contain the idea of a road which is direct and undeviating, the true path of virtue that leads us unswervingly to our destination without straying into byways of temptation.
Oh, dear! And I do love straying into those byways of temptation. Especially when it involves chocolate.