[f. as prec. + -ING2.] That thickens: a. That grows thicker; b. That makes something thick or thicker.
1721. J. Dart, Westminster Abbey, 57. When Learning was with thick’ning Mists o’erspread.
1784. Cowper, Task, IV. 330. Earth receives Gladly the thickening mantle [snow].
1860. Tyndall, Glac., I. xii. 88. At the close of the day thickening clouds warned me off.
1880. Browning, Dram. Idyls, Pan & Luna, 10. Fast-thickening poppy-juice.
1895. Model Steam Engine, 69. The thickening piece is soldered to the boiler.
