Dilate, v. t. [imp. & p. p. Dilated; p. pr. & vb. n. Dilating.]
Etymology: [L. dilatare; either fr. di- = dis- + latus wide, not the same word as latus, used as p. p. of ferre to bear (see Latitude); or fr. dilatus, used as p. p. of differre to separate (see Delay, Tolerate, Differ, and cf. Dilatory): cf. F. dilater.]
1. To expand; to distend; to enlarge or extend in all directions; to swell; -- opposed to contract; as, the air dilates the lungs; air is dilated by increase of heat.
2. To enlarge upon; to relate at large; to tell copiously or diffusely. [R.] Do me the favor to dilate at full What hath befallen of them and thee till now. Shak.
Syn. -- To expand; swell; distend; enlarge; spread out; amplify; expatiate.
2 other Webster entries under this spelling
Dilate, v. i.
1. To grow wide; to expand; to swell or extend in all directions. His heart dilates and glories in his strength. Addison.
2. To speak largely and copiously; to dwell in narration; to enlarge; -- with on or upon. But still on their ancient joys dilate. Crabbe.
Dilate, a.
Extensive; expanded. [Obs.] B. Jonson.
Shades of meaning
Fernald has no entry of its own for dilate; he lists it under amplify.
Where he writes about it:
We may develop a thought, expand an illustration, extend a discussion, expatiate on a hobby, dilate on something joyous or sad, enlarge a volume, unfold a scheme, widen the range of treatment. — from amplify