timely > seasonal pride > {The state of being in flood; stateliness, splendour; tumescence, sexual excitement}
3 His fatty waves do fertile slime outwell,
fatty > oleaginous, greasy; hence: mud-laden, rich outwell > pour forth
4 And overflow each plain and lowly dale: 5 But when his latter spring begins to avale,
latter > last, final spring > tide avale > sink down, flow down
6 Huge heaps of mud he leaves, wherein there breed 7 Ten thousand kinds of creatures, partly male
partly > some
8 And partly female, of his fruitful seed;
seed > semen (cf. 304.41:6); progeny
9 Such ugly monstrous shapes elsewhere may no man read.