along

Etymology

From Middle English, from Old English andlang, from prefix and- + lang (“long”). Doublet of endlong.

prep

1. By the length of; in a line with the length of; lengthwise next to.
   They were waiting for me in the drawing-room, which is a very large room, stretching along the entire front of the house, with three long windows reaching down to the floor 1892, Sir Arthur Conan Doyle, “The Adventure of the Copper Beeches”, in The Adventures of Sherlock Holmes, page 294
   My hopes wa'n't disappointed. I never saw clams thicker than they was along them inshore flats. I filled my dreener in no time, and then it come to me that 'twouldn't be a bad idee to get a lot more, take 'em with me to Wellmouth, and peddle 'em out. Clams was fairly scarce over that side of the bay and ought to fetch a fair price. 1913, Joseph C. Lincoln, chapter 3, in Mr. Pratt's Patients
   As we age, the major arteries of our bodies frequently become thickened with plaque, a fatty material with an oatmeal-like consistency that builds up along the inner lining of blood vessels. 2013 July-August, Stephen P. Lownie, David M. Pelz, “Stents to Prevent Stroke”, in American Scientist
2. In a line with, with a progressive motion on; onward on; forward on.
   In the lightness of my heart I sang catches of songs as my horse gayly bore me along the well-remembered road. 1852, Mrs M.A. Thompson, “The Tutor's Daughter”, in Graham's American Monthly Magazine of Literature, Art, and Fashion, page 266
   Swiftly and silently he made his way along the track which ran through the meadows. 1892, Sir Arthur Conan Doyle, “The Boscombe Valley Mystery”, in The Adventures of Sherlock Holmes, page 93
   We tiptoed into the house, up the stairs and along the hall into the room where the Professor had been spending so much of his time. 1913, Joseph C. Lincoln, chapter 13, in Mr. Pratt's Patients

adv

1. In company; together.
   John played the piano and everyone sang along.
   From The Best of You to The Pretender, their own material invariably came equipped with huge choruses designed to be bellowed along to; they covered Another One Bites the Dust and Under Pressure; they gave every impression of being willing to play all night were it not for the curfew. June 26, 2017, Alexis Petridis, “Glastonbury 2017 verdict: Radiohead, Foo Fighters, Lorde, Stormzy and more”, in the Guardian
2. Onward, forward, with progressive action.
   Don't stop here. Just move along.
   I stumbled along through the young pines and huckleberry bushes. Pretty soon I struck into a sort of path that, I cal'lated, might lead to the road I was hunting for. It twisted and turned, and, the first thing I knew, made a sudden bend around a bunch of bayberry scrub and opened out into a big clear space like a lawn. 1913, Joseph C. Lincoln, chapter 1, in Mr. Pratt's Patients