So repeated with derivations/explanations.

Yule (winter solstice - not part of any month)
This an old term for midwinter festival, probably meaning something like festivities, and related to "jolly"

Afteryule
Easy, month after Yule.

Horning
Referring to the antlers shed by the deer around this period in the year (late winter).

Stirring
The stirring of life in the transition of winter to spring.

Eostrun (spring equinox - not part of any month)
Easter, referring to the (goddess of) dawn or the coming of the sun.

Chithing
Comes from the Bree version of the Shire Calendar of the works of Tolkien. It probably derives from cišing "germinating".

Thrimilch
Month of three milkings (since the pastures are quite good, so the cows give more milk).

Forelithe
Month before Lithe.

Lithe (summer solstice - not part of any month)
From Old English liža, referring to the months of June and July and probably related to liže, meaning "mild".

Afterlithe
Month after Lithe.

Hayweed
Combination of hay and weed in the more general sense of plant.

Harvesting
Self evident.

Gathering (fall equinox - not part of any month)
Referring to the English name of Mabon, the Feast of Ingathering.

Fading
The fading of light and life.

Blooding
The month of slaughter (alternative names for November in Dutch are Slachtmaand - Slaughter Month or Bloedmaand - Blood Month). This is the period in the year where the livestock is thinned to avoid unnecessary food expenses during the winterseason while at the same time provisioning food for that same winter season.

Foreyule
The month before Yule.