Theory:

Meaning of difficult words from "That Sunday Morning":
 
S.No
Words
Meaning
1
PostingGetting appointed or making an entry in a particular place
2
ExploreTo seek or examine something
3
ShadyProviding shade
4
ImposingForcefully make a person perform an action
5
MonumentA memorial; A place to remember famous people, places or objects
6
InvariablyWithout change, every time
7
CrowedTo shout in excitement
8
BillowA large wave or gap caused by wind
9
BlurNot clearly visible
10
GraduallySlowly
11
AchePain
12
SiblingSisters or brothers
13
RivalryFight
14
HazeNot clear
15
WhoopAn explanation, a cry of joy
16
GleeHappiness
17
JammedApply pressure
18
AbruptAll of sudden
19
MomentumThe ability of the body to maintain speed
20
SmackA shark blow
21
RearedTo rise up
22
ClingTo hold on
23
LoomTo rise and show a bigger picture
24
InstinctA natural reaction, without much thinking
25
WhimActing without reasoning or logic
26
LethargicSlow and lazy
27
ResplendentShiny and colorful
28
CavalryMilitary
29
MountedOn horseback 
30
MagnificentGrand
31
ObviousEasily seen 
32
PanickedFeared 
33
StampedeA situation in which many people run around and fall over each other
34
DitchA pit that is dug on the earth
35
DislodgedTo remove
36
TriggeredTo start to initiate an action
37
BellowA deep sound or cry
38
UnfortunateUnlucky
40
ScrambleTo move quickly
41
ThumpRefers to the sound caused by any sudden action
42
AwkwardShameful, difficult
43
TowTo pull any vehicle
44
GrinSmiling widely, showing teeth
45
CommotionGreat noise, something exciting or nasty that happens in a hurry
46
HustleHurrying
47
EmbarrassmentBeing foolish in front of others
48
SightSomething that is seen
49
ThunderousA loud noise or an angry expression
50
ScowlAn angry look
51
ProbabilityChances that something might happen
52
GlanceA quick look
53
HastyFast
54
RetreatTo move or go back
55
EventfulExciting things happening continuously