Names #266, #715 · Viṣṇu Sahasranāma
दुर्धरःdurdharaḥ
Durdhara — appears 2 times in the stotram, each with its own meaning
Name #266
Hard to hold even in the deepest meditation
From shloka 29 · chapter Varāha
सुभुजो दुर्धरो वाग्मी महेन्द्रो वसुदो वसुः ।
नैकरूपो बृहद्रूपः शिपिविष्टः प्रकाशनः ॥
subhujo durdharo vāgmī mahendro vasudo vasuḥ
naikarūpo bṛhadrūpaḥ śipiviṣṭaḥ prakāśanaḥ
Also in this shloka: subhujaḥ · vāgmī · mahendraḥ · vasudaḥ · vasuḥ · naikarūpaḥ · bṛhadrūpaḥ · śipiviṣṭaḥ · prakāśanaḥ
Name #715
Hard to contain, even in meditation
From shloka 76 · chapter Rāma
भूतावासो वासुदेवः सर्वासुनिलयोऽनलः ।
दर्पहा दर्पदो दृप्तो दुर्धरोऽथापराजितः ॥
bhūtāvāso vāsudevaḥ sarvāsunilayo'nalaḥ
darpahā darpado dṛpto durdharo'thāparājitaḥ
Also in this shloka: bhūtāvāsaḥ · vāsudevaḥ · sarvāsunilayaḥ · analaḥ · darpahā · darpadaḥ · dṛptaḥ · aparājitaḥ