The word ‘extravagant’ combines with ‘beckon’, ‘platform’, and ‘summons’ to establish an odd link between Hamlet and Othello. Horatio refers to the disappearing ghost as an “extravagant and erring spirit” (Ham.1.1.154). Roderigo calls Othello an “extravagant and wheeling stranger” (Oth .1. 1. 136). The phonetic, semantic, and rhetorical resemblances between the two phrases are obvious. The adjective ‘extravagant’ appears to have its quite literal Latin meaning of ‘roaming about’. As a fancy Latin word it requires translation (erring/wheeling). ‘Spirit’ and ‘stranger’ have a phonetic relationship through the combination of ‘s’ and ‘r’ with an intervening stop. They are semantically related in that spirits and strangers are outsiders. In the only other occurrence of ‘extravagant’ the adjective is also joined with ‘spirit’ (LLL 4.2.65).

On both occasions the phrase is spoken at night and refers to a nocturnal disruption of daily and orderly life. From that perspective, it is worth looking at some other words that suggests a connection in Shakespeare’s mind between the night scenes of the two plays. The phrases “fearful summons” (Ham.1.1.149) and “terrible summons” (Oth. 1.1.136) occur respectively within five and 54 lines of the word ‘extravagant’. There are only six occurrences of ‘summons’ and ‘extravagant’ in the Shakespeare corpus up to Othello, and it is striking that in four of them the two words are used close to each other.

‘Platform’ is another word with a similar context restriction: in Hamlet it refers to the place where Hamlet will meet the ghost; in Othello it refers to the scene of the drunken brawl (Ham.1.2.213, Ham.1.2.251, Oth.2.3.120). On the platform at Elsinore Hamlet reflects on drunkenness as a Danish vice, and Danes, Hollanders and Germans show up in Iago’s conversation with Cassio (Oth. 2.3.73).

Finally, and more speculatively, there is the verb ‘beckon’. When the ghost
beckons (Ham.1.4.58), Horatio implores Hamlet not to follow his temptation.
Hamlet rejects the advice but keeps his guard against the Ghost’s words. Othello watches Iago’s conversation with Cassio and is only too eager to follow Iago’s gesture: “Iago [beckons] me; now he begins the story” (Oth. 4.1. 130).

Outside of Hamlet and Othello the words discussed here
occur in the following plays:

beckon: 1H6 1.4.92, Tro. 5.3.53, Tim.1.1.74, TNK 1.5.129
extravagant: LLL 4.2.66, TNK 4.3.73
platform: 1H6 2.1.77
summons: Ri2 1.3.4, KiL 5.3.121, Mac. 2.1.6, Mac. 3.2.41, Tem 4.1.131, He8

Of the 22 tokens of these four word types, 9 occur in Hamlet and Othello. If we look only the corpus up to and including Othello, 9 of 14 tokens occur in the two plays. It is odd but probably coincidental that ‘beckon’ and ‘platform’ occur
relatively closely to each other in the early Talbot scenes of 1Henry VI. Nonetheleless, the use of the word ‘beckon’ is intriguing: Talbot uses it to describe the seeming motion of the dead Salisbury urging him to revenge for the French plot that cost his life:

89 Speak unto Talbot, nay, look up to him.
90 Salisbury, cheer thy spirit with this comfort,
91 Thou shalt not die whiles —
92 He beckons with his hand and smiles on me,
93 As who should say, “When I am dead and gone,
94 Remember to avenge me on the French.”
(1H6 1.4.89-94)

One can argue that Shakespeare’s use of ‘beckon’ has a distinctively intense and supernatural inflection. In the context of the passages from 1Henry VI and Hamlet, Iago’s beckoning becomes a truly diabolic gesture.

Other words that occur only in Hamlet and Othello, but without interesting context restrictions, include ‘comply,’ ‘indict’, ‘recognizance’, ‘unforced’, the uses of ‘whore’ and ‘timber’ as verbs, and the phrase ‘knock over/about the mazzard’.