Some join in the wilderness with make straight, as in the Hebrew. The quotation is from Isa 40:3. In the other three Gospels it is applied to the Baptist (Mat 3:3; Mar 1:3; Luk 3:4). Here he uses it of himself. On wilderness, see on Mat 3:1.
Make straight the way (εὐθύνατε τὴν ὁδὸν)
For ὁδὸν, way, all the Synoptists have τρίβους, beaten tracks; and for the verb εὐθύνατε, make straight, the adjective and verb εὐθύνατε ποιεῖτε. On the figure of preparing the roads, see on Luk 3:5.