"Mon beau-frère lave ses chemises."
Translation:My brother-in-law is washing his shirts.
There may be three issues here. 1. My Webster's dictionary and Larousse say stepbrother has no hyphen. DL may not accept step-brother. Edit: But I've now found examples in Family where DL spells stepbrother both with and without a hyphen. 2. DL is apparently still not accepting "is washing." See multiple comments and reports. 3. Beau-frère = brother-in-law. Larousse says stepbrother = demi-frère. Can beau-frère also = stepbrother?
I don't know about in French but in English you are related biologically to a half brother (shares one biological parent), whereas a step brother is unrelated to you by blood. So does half brother = demi-frére and step brother = beau frére or is there any distinction between the two in French.
Dear site maintainers, there is a problem with this translation. Due to the ambiguous use of beau-frere to translate as either brother-in-law or step-brother depending on context, and the absence of said context in this sentence, the correct translation should be "brother by marriage". A this statement similarly does not imply whose marriage forms the relation.